# COORDINATING RESEARCH COUNCIL, INC.

3650 MANSELL ROAD · SUITE 140 · ALPHARETTA, GA 30022 

# CRC Report No. E-74b

EFFECTS OF VAPOR PRESSURE, OXYGEN CONTENT, AND TEMPERATURE ON CO EXHAUST EMISSIONS



# May 2009The Coordinating Research Council, Inc. (CRC) is a non-profit corporation supported by the petroleum and automotive equipment industries. CRC operates through the committees made up of technical experts from industry and government who voluntarily participate. The four main areas of research within CRC are air pollution (atmosphericand engineering studies); aviation fuels, lubricants, and equipment performance, heavyduty vehicle fuels, lubricants, and equipment performance (e.g., diesel trucks); and lightduty vehicle fuels, lubricants, and equipment performance (e.g., passenger cars). CRC’s function is to provide the mechanism for joint research conducted by the two industries that will help in determining the optimum combination of petroleum products and automotive equipment. CRC’s work is limited to research that is mutually beneficial to the two industries involved, and all information is available to the public.

CRC makes no warranty expressed or implied on the application of information contained in this report. In formulating and approving reports, the appropriate committee of the Coordinating Research Council, Inc. has not investigated or considered patents which may apply to the subject matter. Prospective users of the report are responsible for protecting themselves against liability for infringement of patents.

# Report No. SR2009-05-03



# Effects of Vapor Pressure, Oxygen Content, and Temperature on CO Exhaust Emissions

prepared for: 

# Coordinating Research Council

May 18, 2009

prepared by:

Sierra Research, Inc. 1801 J Street Sacramento, California 95811 (916) 444-6666

### Report No. SR2009-05-03



## Effects of Vapor Pressure, Oxygen Content, and Temperature on CO Exhaust Emissions

prepared for:

Coordinating Research Council

May 18, 2009

Robert Crawford Rincon-Ranch Consulting

Harold Haskew Harold Haskew & Associates

Jeremy Heiken Dennis McClement James Lyons Sierra Research, Inc. 1801 J Street Sacramento, CA 95811 (916) 444-6666

### -i

## Effects of Vapor Pressure, Oxygen Content, and Temperature on CO Exhaust Emissions

Table of Contents

Page

1. Executive Summary ........................................................................................................1

2. Introduction .................................................................................................................. ...6

3. Test Program ...................................................................................................................7
3.1 Test Vehicles ............................................................................................................7 3.2 Pretest Procedures ..................................................................................................10 3.3 Test Procedures ......................................................................................................10 3.4 Test Fuels ...............................................................................................................12

4. Data Analysis ................................................................................................................1 6
4.1 Overview of Experimental Design .........................................................................16 4.2 Vehicle Technology Groups ..................................................................................17 4.3 Test Fuels ...............................................................................................................18 4.4 Statistical Analysis Methodology ..........................................................................22 4.5 Analysis of Oxygenate Effects on CO Emissions..................................................23 4.6 Analysis of RVP Effects Between 7 and 9 psi at 75°F ..........................................28 4.7 Analysis of the Effect of Increasing RVP from 9 psi to 13 psi at 75°F .................33 4.8 Analysis of Impact of Increasing RVP from 9 psi to 13 psi at 50°F .....................36

5. STATISTICAL ANALYSIS and Development of Emission CorRection Factors .......42

5.1 Overview ................................................................................................................42 5.2 Methodology ..........................................................................................................42 5.3 Statistical Analysis Results (Primary) ...................................................................47 5.4 Alternative Statistical Analysis ..............................................................................62 5.5 Summary of Correction Factors Based on Primary Analysis ................................75 5.6 Comparison of Adjustment Factors to Those in MOBILE6.2 ...............................81 5.7 Comparison of RVP and Oxygenate Effects to Those of Previous Sierra Study ..85

6. COMPARISON OF MOBILE6.2 AND UPDATED CO ADJUSTMENT FACTORS........................................................................................................................ ..87

6.1 Methodology ..........................................................................................................87 6.2 Results ....................................................................................................................92

Appendix A – Sulfur Removal Protocol Used in Testing Appendix B – Additional Vehicle and Te st Information and Emissions Data

### -iiList of Figures

Figure Page

Figure ES-1 2010 Winter On-Road CO Emission Inventory for Clark County, Nevada as a Function of Oxygenat e Level ....................................................................3 Figure ES-2 Effects of Ethanol Content on Composite FTP Emissions in the E-74b Project ....................................................................................................................... .....5 Figure 3-1 Fuel Ethanol, Vapor Pressure , and Temperature Combinations Tested .........15 Figure 4-1 Experimental Fuel Form ulation for RVP and Oxygen Content ......................20 Figure 4-2 Oxygenate Effect by FTP Phase and Technology for RVP 9 Fuels at 75°F .......................................................................................................................... ....27 Figure 4-3 Example of CO Emi ssions Trends with RVP at 75°F ....................................28 Figure 4-4 7 RVP Effect by FTP Phase and Technology at 75°F Compared to 9 RVP Fuels ....................................................................................................................3 1 Figure 4-5 Oxygenate Effect by FTP Phase and Technology for RVP 7 to 9 Fuels at 75°F ..........................................................................................................................32 Figure 4-6 Impacts of 13 RVP Fuel by FTP Phase and Vehicle Group at 75°F Relative to 9 RVP Fuel ................................................................................................35 Figure 4-7 Oxygenate Effects by FTP Phase and Technology 9 to 13 RVP Fuels at 75°F .......................................................................................................................... ....37 Figure 4-8 Effects of 13 RVP Fuel by FTP Phase and Technology at 50°F Relative to RVP 9 Fuels .............................................................................................................39 Figure 4-9 Oxygenate Effects by FTP Phase and Technology for 9 to 13 RVP Fuels at 50°F ..........................................................................................................................41 Figure 5-1 Group 1, Bag 1 CO Trends .............................................................................76 Figure 5-2 Group 1, Bag 2 CO Trends .............................................................................77 Figure 5-3 Group 1, Bag 3 CO Trends .............................................................................77 Figure 5-4 Group 4, Bag 1 CO Trends .............................................................................78 Figure 5-5 Group 4, Bag 2 CO Trends .............................................................................78 Figure 5-6 Group 4, Bag 3 CO Trends .............................................................................79 Figure 6-1 Las Vegas Typical Winter Day Diurnal Profiles ............................................88 Figure 6-2 Winter On-Road CO Emission Inventory for Clark County, Nevada 9 RVP Gasoline...............................................................................................................93 Figure 6-3 2010 Winter On-Road CO Emission Inventory for Clark County, Nevada as a Function of RVP ......................................................................................94 Figure 6-4 2010 Winter On-Road CO Emission Inventory for Clark County, Nevada as a Function of Oxygenat e Level ..................................................................94

### -iiiList of Tables

Table Page

Table ES-1 Summary of Statistically Significant Relationships a 

### Observed Between FTP Composite Emissions and Test Variables ..............................................................2 Table 3-1 Test Vehicle Descriptions...................................................................................8
Table 3-2 Test Vehicle Emi ssion Certifica tion Classes ......................................................9 Table 3-3 Original Fu el Blending Targets ........................................................................12 Table 3-4 Fuel Properties (Average from sponsors) .........................................................13
Table 3-5 Additional Fuel Pr operties (from Haltermann) ................................................14 Table 4-1 Average Emission Rate s by Technology Group (g/mile)..................................18 Table 4-2 Effect of Fuel Oxygen Content on CO Emissions ............................................25
Table 4-3 Effect of Low Gasoline RVP on CO Emissions ...............................................29 Table 4-4 Effect of High Gasoline RVP on CO Emissions ..............................................34 Table 4-5 Effect of High Gasoline RVP on CO Emissions ..............................................38 Table 5-1 Model Summary for CO FTP Composite .........................................................50 Table 5-2 Model Summary for CO FTP Bag 1.................................................................51 Table 5-3 Model Summary for CO FTP Bag 2.................................................................52 Table 5-4 Model Summary for CO FTP Bag 3.................................................................53 Table 5-5 Model Summary for THC FTP Composite ......................................................54 Table 5-6 Model Summary for THC FTP Bag 1 ..............................................................55 Table 5-7 Model Summary for THC FTP Bag 2 ..............................................................56 Table 5-8 Model Summary for THC FTP Bag 3 ..............................................................57 Table 5-9 Model Summary for NOx FTP Composite ......................................................58 Table 5-10 Model Summary for NOx FTP Bag 1 ............................................................59 Table 5-11 Model Summary for NOx FTP Bag 2 ............................................................60 Table 5-12 Model Summary for NOx FTP Bag 3 ............................................................61
Table 5-13 Alternative Mode l for CO FTP Composite ....................................................63
Table 5-14 Alternative M odel for CO FTP Bag 1 ............................................................64
Table 5-15 Alternative M odel for CO FTP Bag 2 ............................................................65
Table 5-16 Alternative M odel for CO FTP Bag 3 ............................................................66
Table 5-17 Alternative Mode l for HC FTP Composite ....................................................67 Table 5-18 Alternative Model for HC FTP Bag 1 ............................................................68 Table 5-19 Alternative Model for HC FTP Bag 2 ............................................................69 Table 5-20 Alternative Model for HC FTP Bag 3 ............................................................70
Table 5-21 Alternative Mode l for NOx FTP Composite ..................................................71 Table 5-22 Alternative Model for NOx FTP Bag 1 ..........................................................72 Table 5-23 Alternative Model for NOx FTP Bag 2 ..........................................................73

### -ivTable 5-24 Alternative Model for NOx FTP Bag 3 ..........................................................74
Table 5-25 Correction Factor Coefficients for FTP CO Emissions ...................................75 Table 5-26 Estimated Effects of Design Variables on FTP CO Emissions (Compared to Design Variable Conditions Stated, Percent) .......................................75
Table 5-27 Correction Factor Coef ficients for FTP THC Emissions ...............................79 Table 5-28 Estimated Effects of Design Variables on FTP THC Emissions ....................80
Table 5-29 Correction Factor Coefficients for FTP NOx Emissions ................................81
Table 5-30 Estimated Effects of Desi gn Variables on FTP NOx Emissions ....................81 Table 5-31 Comparison of CO Adjus tment Factors to MOBILE6.2 Factors ...................82 Table 5-32 Comparison of THC Adjus tment Factors to MOBILE6.2 Factors.................83 Table 5-33 Comparison of NOx Adjus tment Factors to MOBILE6.2 Factors .................84 Table 5-34 Comparison of RVP and Temperature Adjustment Equation Coefficients for FTP Composite Exhaust CO Emissions ............................................86 Table 5-35 Estimated Impact of Re ducing RVP from 11.7 to 9.0 psi on FTP Composite CO Emissions ............................................................................................86
Table 6-1 Wintertime Gasoline Fuel Requirements for Clark County .............................89
Table 6-2 Winter 2006 Ga soline Parameters ...................................................................89 Table 6-3 Comparison of Las Vegas Winter On-Road CO Inventory Based on MOBILE6.2 and Updated Adjustment Factors (tons per day) ....................................93 Table 6-4 Comparison of E-74b and MO BILE6.2 Emission Rates FTP Composite CO Exhaust Emissions at Standa rd Conditions (grams per mile) ...............................96

### -1- 

## 1. EXECUTIVE SUMMARY

In response to the Clean Air Act Amendmen ts of 1990, both Phoenix, Arizona and Las Vegas, Nevada areas were designated as being in nonattainment with the National Ambient Air Quality Standard (NAAQS) for carbon monoxide (CO). Both areas implemented regulations requiring winter gasolines to contain 3.5 percent oxygen by weight and limiting Reid Vapor Pressure (RVP) to 9 psi in order to reduce CO emissions from on-road motor vehicles. However, th e regulations also created fuel property requirements that differed from those in place throughout the rest of the southwest, including California, and this tended to re duce the flexibility of the fuel supply and distribution system to provide gasoline in Phoenix and Las Vegas during the winter. Despite the fact that ambient CO concentrations have not exceeded the NAAQS in either area for a number of years, both areas continue to enforce these fuel regulations. One reason why the regulations remain in place is that the U.S. Environmental Protection Agency (EPA)’s MOBILE6.2 emission factor mo del predicts that the elimination of the oxygenate requirements and RVP restrictions will result in large increases in CO emissions from on-road mobile sources.

In 2003, Sierra Research (Sierra) reviewed the adjustment methodology used in MOBILE6, a predecessor to MOBILE6.2, to account for the impacts of oxygenate and RVP on CO emissions under winter conditions. * 

### Sierra found that the oxygenate adjustment methodology had been recently updated using data from 1988 and later model-year vehicles certified to Tier 1 ex haust emission standards and concluded that it was reasonable. In contrast, Sierra f ound that the RVP methodology was originally developed for use in the now outdated MO BILE4 and MOBILE5 models using data acquired from early 1980s model-year vehicles and that it appeared to overpredict the increase in CO emissions associated with an increase in RVP relative to alternative correction factors developed by Sierra that included more recent data. The oxygenate and RVP adjustment methodologies that Sierra re viewed in MOBILE6 have been carried over by U.S. EPA into MOBILE6.2.

Since the last time either the U.S. EPA oxygenate and RVP adjustment methodologies were revisited by the agency and Sierra’s 2003 study, vehicles certified to much more stringent exhaust and evaporative emission c ontrol standards have entered the fleet in large numbers and their populations will continue to expand. Given this, and the fact that the U.S. EPA methodologies generally rely on data from older vehicles, the Coordinating Research Council (referred to here as Sponsors) funded the E-74b vehicle testing

* Heirigs, P.L., and Lyons, J.M, “Review of Current and Future CO Emissions from On-Road Vehicles in Selected Western Areas,” Sierra Research Report No. SR03-01-01, January 28, 2003.

### -2- program. The E-74b program was designed primarily to evaluate the effects of RVP and oxygenate content on exhaust CO emissions under conditions similar to those found in the Phoenix and Las Vegas areas during the winter on recent model-year vehicles. Therefore, test vehicles sel ected for the E-74b program were certified to Tier 1 and more stringent exhaust emission standards and both enhanced and so-called “zero” evaporative emissions standards. Similarly, the test fuel matrix included fuels with RVP levels varying from 9 to 13.3 psi and oxygenate content ranging from zero to 3.5 weight percent, and emissions testing was performed at both 75°F and 50°F. In addition to the RVP and oxygenate matrix, an E20 test fuel was included in the test fuel matrix to examine the emission effects of increasing gasoline ethanol content beyond the current E10 limit.

A complete statistical analysis of the ve hicle emissions and fuel property data was conducted. The results of this analysis rev ealed statistically significant relationships between test variables and CO, THC, and NOx emissions. These relationships are summarized in Table ES-1 in terms of the directional change in the test variable and the directional impact on emissions. Note that th e same directional changes in primary test variables are also applicable to the four combinations of test variables.

Table ES-1 Summary of Statistically Significant Relationships a 

### Observed Between FTP Composite Emissions and Test Variables
Variables CO THC NOx Temperature (decreasing from 75°F) + b 

### + + Oxygen Content (increasing from 0 wt%) - c 

### - + RVP (increasing from 9 psi) + + Temperature and Oxygen Content + RVP and Oxygen Content RVP and Temperature - Oxygen Content Squared +

a At 95% or greater confidence level.
b + Indicates increasing emissions.

c - Indicates decreasing emissions.



### Based on the results of the statistical anal ysis, updated adjustments for RVP, oxygenate and temperature impacts under moderate wint er conditions were developed from the E-74b data. These updated adjustments were substituted for those used in MOBILE6.2, and the impacts of this substitution were evaluated on the wintertime CO inventory for

### -3- the Las Vegas area. * 

### The results of this evaluation i ndicate that, for late-model vehicles operating under wintertime cond itions, MOBILE6.2 currently:

1. Overestimates CO emissions;

2. Underestimates the impact of increasing oxygenate content in reducing CO emissions; and

3. Overestimates the impact of increasing RVP in increasing CO emissions.

The magnitude of the differences between the current MOBILE6.2 adjustments and those developed based on the data collected in this project can be seen in Figure ES-1.

Figure ES-1 2010 Winter On-Road CO Emission Inve ntory for Clark County, Nevada as a Function of Oxygenate Level

200 250 300 350 400 450 500 550 600 650 700

200 250 300 350 400 450 500 550 600 650 700

0 2.7 3.5 0 2.7 3.5COTPDCOTPD



### % OXYGEN % OXYGEN 

### 2010 MOBILE 6.2 2010 Updated Adjustments

9 RVP
11.7 RVP
13.3 RVP

* The Las Vegas area was selected for this comparison for several reasons. First, it, along with the Phoenix, Arizona area, represents one of the two major urban areas where regulations requiring winter gasoline to contain 3.5 percent oxygen by weight and limiting RVP to 9 psi were implemented in order to reduce CO emissions from on-road vehicles. Next, because limited project resources precluded comparisons in both areas, it was selected over Phoenix due to the availability of the emission inventory data required to perform the comparison.

### -4- Figure ES-1 shows the 2010 winter CO e mission inventory for Clark County (Las Vegas), Nevada as a function of RVP and fuel oxygen content estimated using MOBILE6.2 with the existing oxygen, RVP a nd temperature adjustment factors and those developed under this study. The ge neral overestimation of CO emissions by MOBILE6.2 relative to the results of this stud y can be seen by the displacement of the constant RVP lines on the right and left side s of the figure. Most notably, with the updated adjustment factors, even the high est estimated CO emissions under the 13.3 RVP and no oxygen case are lower than those estimated by MOBILE6.2 for the lowest CO emissions case at 9 RVP and 3.7 weight percent oxygen.

Next, as can be seen by the space between the constant RVP lines, for an RVP increase from 9 to 13.3 psi the updated adjustment factor s predict an increase in CO emissions of about 15%, which is less than one-half of the 35% increase currently predicted by MOBILE6.2. Finally, as can also be seen fr om the slopes of the constant RVP lines as oxygenate content is increased, the updated adjustment factors predict a much greater reduction in CO emissions with increasing oxygenate content than that currently predicted by MOBILE6.2. Moving from 9 RV P and no oxygen to 9 RVP and 3.5 percent oxygen by weight, the updated adjustment s show about a 23% reduction in the CO inventory. Using MOBILE6.2, this same chan ge in oxygen content would be estimated to reduce the CO inventory by only about 8%. Ov erall, the results of this study show that (1) CO emissions in Las Vegas are consid erably lower than estimated by MOBILE6.2; (2) removal of the RVP limit in Las Vegas would have a smaller effect in terms of the percentage increase in CO emissions than predicted by MOBILE6.2; and (3) elimination of the winter oxygenate requirements in Las Vegas would have a larger effect, again in terms of the percentage increase in CO emissions, than predicted by MOBILE6.2. Although CO emissions in the Phoenix ar ea were not explicitly evaluated, similar findings would be made using the updated adjustments developed from the E-74b data.

As noted above, in addition to allowing for the evaluation of the RVP and oxygen adjustment factors under winter conditions in the Las Vegas and Phoenix areas, the data collected during the E-74b test program provide insight with respect to another important question—the effect of increasing the ethanol content of gasoline above 10% by volume on exhaust emissions. This was possible because of the inclusion of an E20 test fuel in the test fuel matrix. However, the results may be confounded to some degree because of variation in the distillation properties of the E20 test fuel relative to the other test fuels in the project.

Figure ES-2 shows the estimated change in exhaust emissions of total hydrocarbons (THC), CO, and oxides of nitrogen (NOx) as a function of oxygen content at 75°F and 9 RVP. As shown in the figure, analysis of emissions data from the late-model vehicles tested in the E-74b project indicates that increasing ethanol (and therefore oxygen) content leads to reduced exhaust emissions of THC and CO and in creased emissions of NOx. For THC and NOx, the relationships be tween changes in emissions and ethanol content found in the E74b data are linear. In contrast, for CO the relationship is nonlinear, with diminishing changes in CO emi ssions resulting from increasing the amount of ethanol added.

### -5- Figure ES-2 Effects of Ethanol Content on Composit e FTP Emissions in the E-74b Project

###

### -6- 

## 2. INTRODUCTION

The effects caused by changes in gasoline RVP and oxygen content on exhaust emissions have been of concern for quite some time and adjustments to account for these effects were incorporated into the U.S. EPA’s MOBI LE series of emission factor models during the 1980s and 1990s. In general, the MOBI LE adjustments for RVP and oxygenate effects are based on older model-year vehicl es and have not been updated with data obtained from newer model-year vehicles certified to more stringent exhaust and evaporative emissions standards. As a c onsequence of these MOBILE adjustments, Phoenix, Arizona and Las Vegas, Nevada area s implemented regulations requiring winter gasolines to contain 3.5 percent oxygen by weight and limiting Reid Vapor Pressure to 9 psi in order to reduce CO emissions from on-road motor vehicles. As noted previously, these regulations also created fuel property requirements that differed from those in place throughout the rest of the southwest, includi ng California, and this tended to reduce the flexibility of the fuel supply and distributi on system to provide gasoline in Phoenix and Las Vegas during the winter.

Given the above, the Coordinating Research Council (referred to here as Sponsors) funded the E-74b vehicle testing program design ed primarily to evaluate the effects of RVP and oxygenate content on exhaust CO emissions under conditions similar to those experienced in the Las Vegas and Phoenix ar eas during winter months. Given their prevalence in the in-use vehicle fleet, this testing focused on recent model-year vehicles certified to Tier 1 and more stringent exha ust emission standards and both enhanced and so-called “zero” evaporative e missions standards. This proj ect involved vehicle testing, a complete statistical analysis of the data , and the development of updated adjustment factors for RVP and oxygenate effects on exha ust emissions. In addition, because an E20 fuel was added to the test fuel matrix, the re sults of the E-74b project provide insight into the exhaust emission impacts that would be associated with an increase in the allowable ethanol content of gasoline beyond the cu rrent limit of ten percent by volume.

The subsequent sections of this report describe the test progr am, data analysis, statistical analysis and development of adjustment s, and evaluation of the updated RVP and oxygenate adjustments on the wintertime CO emission inventory in the Las Vegas area. The catalyst sulfur removal protocol used in the project is presented in Appendix A and all vehicle test data collected during the project are presented in Appendix B. Finally, an assessment of test-to-test variability in the E-74b project is presented in Appendix C.

###

### -7- 

## 3. TEST PROGRAM

3.1 Test Vehicles

Detailed vehicle fleet specifi cations were provided by the sponsors of the E-74b program. The vehicle definition included make, mode l year, engine size, and exhaust and evaporative emission certification classes. The vehicles tested exactly met the requested vehicle specifications.

Test vehicles were purchased from local Arizona dealers and private parties specifically for use in this program. They were select ed to include representative high sales volume samples based on emission control system/manufacturer/engine size categories. Accumulated odometer mileages were appropriate for the model year procured, ranging from 28,000 miles to 104,000 miles. The vehicle model years ranged from 1994 to 2006.

A detailed under hood visual inspection was performed prior to purchase. Vehicles that had been modified, or that showed signs of extensive damage and repair, were not to be procured. In particular, the catalytic conver ter and engine emission control systems were inspected to ensure they were intact, and that their apparent age and condition were appropriate for the candidate vehicle. The operation of the vehicle’s brakes and transmission was verified to ensure testability. Table 3-1 describes the test vehicles in the program. Table 3-2 provides additional de tail regarding the certification standards applicable to the test vehicles selected.

As shown in Table 3-2, the test vehicles were certified to either federal Tier 1, National Low Emission Vehicle (NLEV), or Tier 2 exha ust emission standards. In addition, most of the vehicles were certified as being in compliance with the federal Cold Temperature CO requirements. With respect to evaporativ e emissions, test vehicles were certified to either the pre-enhanced (e.g., one-hour diurnal), enhanced, or near-zero emission standards.-8-Table 3-1Test Vehicle DescriptionsVeh No MY Make Model Type Trans Displacement (l) Odometer Tank Volume (gal)001 1994 Chevrolet Lumina PC Auto 3.1 81,512 16.0002 1996 Ford Taurus PC Auto 3.0 86,538 16.0003 1995 Jeep Cherokee LDT Man/5 4.0 98,668 20.0004 1999 Honda Accord PC Auto 2.3 100,414 17.1005 2001 Toyota Corolla PC Auto 1.8 92,047 13.2006 2002 Nissan Altima PC Auto 2.5 104,712 20.0007 2001 Dodge Caravan LDT Auto 3.3 92,740 20.0008 2002 Chevrolet Trail Blazer LDT Auto 4.2 58,618 18.6009 2004 Dodge Stratus PC Auto 2.4 63,184 16.0010 2004 Chevrolet Impala PC Auto 3.4 57,604 17.0011 2004 Toyota Camry PC Auto 3.0 42,592 17.2012 2006 Ford Taurus PC Auto 3.0 28,354 18.0013 2004 Dodge Ram 1500 SLT LDT Auto 4.7 96,11935.0014 2004 Ford Escape LDT Auto 3.0 40,188 16.0015 2004 Toyota Highlander LDT Auto 3.3 88,693 19.1-9-Table 3-2Test Vehicle EmissionCertification ClassesVeh No Model Year Make Exhaust StandardStandardsa(g/mile)Cold CO Standards(g/mile) Evap Standard001 1994 Chevrolet Tier 1 LDV .31/4.2/.6 N/APre Enhanced002 1996 Ford Tier 1 LDV .31/4.2/.7 10.0 Enhanced003 1995 JeepTier 1 LDT2 .40/5.5/0.97 N/APre Enhanced004 1999 Honda NLEV LEV .09/4.2/.3 10.0 Enhanced/ORVR005 2001 Toyota NLEV LEV .09/4.2/.3 10.0 Enhanced/ORVR006 2002 Nissan NLEV ULEV .055/2.1/.3 10.0 Enhanced/ORVR007 2001 Dodge NLEV LEV LDT2 .13/5.5/.5 12.5 Enhanced/ORVR008 2002 Chevrolet NLEV LEV LDT2 .13/5.5/.5 12.5 Enhanced/ORVR009 2004 DodgeTier 2 Bin 5 .09/4.2/.07 10.0 Enhanced/ORVR010 2004 Chevrolet Tier 2 Bin 5 .09/4.2/.07 10.0 Enhanced/ORVR011 2004 ToyotaTier 2 Bin 9 .09/4.2/.30 10.0 Near Zero/ORVR012 2006 FordTier 2 Bin 5 .09/4.2/.07 10.0 Near Zero/ORVR013 2004 Dodge Tier 2 Bin 10 LDT .23/6.4/.60 12.5 Enhanced/ORVR014 2004 FordTier 2 Bin 9 .09/4.2/.30 10.0 Near Zero/ORVR015 2004 ToyotaTier 2 Bin 5 .09/4.2/.07 10.0 Near Zero/ORVRaStandards are given as NMHC/CO/NOx

### -10- 

## 3.2 Pretest Procedures

All exhaust emission testing in this project was performed using the U.S. EPA’s standard “Federal Test Procedure” (FTP). An FTP exhaust emission test wa s performed to assess vehicle condition upon arrival at the testing labo ratory. The results were reviewed with Harold Haskew and Associates before continui ng. The in-use compliance of the vehicles with their very stringent certification standa rds was notable. No e missions-related repairs were required prior to testing.

The fuel tank temperatures encountered durin g vehicle operation strongly influence the rate of fuel vapor generation. Emission testing is performed on a chassis dynamometer. Left uncontrolled, fuel tank temperatures occu rring during dynamometer operation can be unrepresentatively high or low. Exhaust e mission CO levels encountered with Tier 0 vehicles were believed to be influenced by fuel vapors purged by the engine from the evaporative emission control canister. The temperature of the gasoline during FTP testing in this program was th erefore monitored and controlled.

An on-road fuel tank temperature profile appr opriate for FTP testing at 50° and 75°F was measured. Each test vehicle was instrumented with external fuel tank thermocouples, drained and filled to 40% ta nk capacity, preconditioned with one LA4 road equivalent, and soaked overnight. The vehicle was then operated on the road through the equivalent of the dynamometer FTP cycle while fuel tank temperatures were monitored. These temperature data were used to develop fuel temperature targets for use during dynamometer emission testing.

A special preconditioning cycle was performed before the first test fuel cycle to minimize the effect of residual catalyst sulfur depos its resulting from operation with uncontrolled commercial fuels. A description of the sulf ur preconditioning is provided in Appendix A.

Individual random test orders were created for each vehicle prior to the start of testing. The various combinations of fuel RVP, etha nol level, and ambient temperatures were performed in the predetermined order. The detailed test results, pr ovided in Appendix B, include the run number for the individual tests.



## 3.3 Test Procedures

Vehicles received extensive preconditioning prior to each test. The preconditioning served to normalize both the exhaust emission control adaptive learning function and fuel carryover effects in the evaporative emission control charcoal canister.

Vehicle preconditioning began with caniste r normalization. The canister received a 300 bed volume purge with room air at a nomin al flow rate of 0.4 cfm. The vehicle evaporative service port (or a tee installed for the purpose) was used for the purge. One liter of the fuel type to be used for the emissi on test was then placed in a sealed container. The container was mounted on a laboratory dig ital scale. Nitrogen was bubbled through

### -11- the fuel, and the saturated vapor was directed to the service port and canister of the vehicle being tested. Canister loading continued until the weight of the fuel sample had been reduced by an amount equal to 25% of the vehicle canister capacity. For example, a canister with a 120-gram working capacity was loaded with 30 grams of fuel vapor. The rate of nitrogen flow was controlled to mainta in a nominal rate of fuel weight change of 40 grams/hour. Rates were adjusted to main tain a purge/load cycle within a two-hour limit.

The vehicle was then drained and refueled w ith as-received tank fuel to 40% capacity with the fuel specified for the upcoming test. The vehicle was operated over three cycles of a 7.6-mile road course. The operation included mixed city street and expressway driving, with an average speed similar to the dynamometer LA4 cycle used for FTP testing. The vehicle was then parked in the laboratory at a nominal temperature of 75°F. A final drain and 40% fill with the same fu el was performed. The dynamometer test cell and soak area were set at the temperature specified for the upcoming test. The final LA4 preconditioning was performed and the vehicle was placed in the controlled temperature soak area.

Soak time between the end of the prec onditioning and the start of the FTP was maintained between 18 and 22 hours. At th e end of the soak period, the vehicle was transferred to the emission test cell. An FTP test was performed in accordance with new vehicle certification procedures. Enhancemen ts included use of an INNOVA analyzer to measure ethanol in the exhaust and second -by-second emissions measurements before and after the catalytic converter. The cell temp erature was set at 50° or 75°F, as specified in the randomized testing schedule. Emi ssions of CO, THC, non-methane hydrocarbons (NMHC), NOx, and carbon dioxide (CO 2 

### ) were measured and reported in grams and grams/mile. The ethanol component of th e hydrocarbon emissions was handled as specified in the California Air Re sources Board (CARB) procedures * 

### cited in the federal regulations.

Fuel temperatures were controlled during the final LA4 and FTP tests. The temperature rise observed during the initial road test would be applied to the ambient temperatures maintained during each test on a vehicle. An 8°F fuel temperature rise observed during the initial road LA4 would translate to a rise from 50° to 58°F during a 50°F dynamometer test. Under-vehicle air flow was adjusted to maintain the fuel temperature profile observed during road operation.

Data from each preconditioning and test series were carefully reviewed for completeness and conformance to all quality specifications. The test vehi cle would be scheduled for the next randomly selected test in th e series following test acceptance.

* California Non-Methane Organic Gas Test Procedures, July 12, 1991, amended July 30, 2002, California Air Resources Board, Monitoring and Laboratory Division. http://www.arb.ca.gov/msprog/levprog/cle andoc/clean_nmogtps_final.pdf

### -12- 

## 3.4 Test Fuels

The test fuels were specifically prepared for this program. The RVP of the finished fuels was targeted at levels of 7.0, 9.0, and 13.0 psi. Ethanol contents of E0, E10, and E20 were specified. The base stocks for the E10 and E20 fuels were intended to yield appropriate RVP a nd other properties following addition of the ethanol.

The fuels were prepared by Haltermann Produc ts of Channelview, Texas. The average inspection properties of wint er-grade conventional gasolin e blended with ethanol, as reported in the 2002-2003 Northrop Grumma n (formally NIPER) gasoline survey, * 

### were supplied as targets. Table 3-3 displays the survey results. Initially only two batches of fuel were to be tested, and all properties, except RVP, were to be “closely matched.” Both fuels were to contain 10% ethanol. The program was later expanded to include seven different combinations of fuel RVP a nd ethanol content. As a result, the fuel properties at the highest RVP and highest etha nol contents were no longer as “close” as those of the lower RVP and ethanol fuels.

The fuels were to be blended from standard re finery streams. Samples of the finished fuels were analyzed by several of the test s ponsors. Table 3-4 displays the results of the analyses performed by the sponsors. Table 3- 5 displays additional analysis performed by the fuel blender.

Table 3-3 Original Fuel Blending Targets Property Limits Test Method Gravity, °API Report ASTM D 287
DVPE 9.0, 13.0 ASTM D 5191 T10 Varies w/DVPE ASTM D 86 T50 158-168 F ASTM D 86 T90 315-325 F ASTM D 86
FBP < 437 F ASTM D 86 RON 91-95 ASTM D 2699 MON 83-87 ASTM D 2700 (R+M)/2 87-91 Aromatics 21-25 vol% ASTM D 1319 (Vol %), or D 5580 (Wt %)
Benzene 0.9-1.1 vol % ASTM D 5580 or D 3606 Olefins 7-11 vol% ASTM D 1319 (Vol %), or D 6550 (Wt %) Sulfur 25-30 ppm ASTM D 2622 Ethanol 10 vol% ASTM D 4815

* “Motor Gasolines, Winter 2002-03,” Cheryl Dickson, August 2003, Northrop Grumman, Bartlesville, OK, NGMS-230 PPS 2003/3-13-Table 3-4Fuel Properties (Average from sponsors)Inspection Units Fuel 6 Fuel 3 Fuel5 Fuel 7 Fuel 1 Fuel 2 Fuel 4API Gravity °API 60.2 63.3 64.1 58.5 58.8 59.7 57.0Relative Density 60/60°F 0.7381 0.7262 0.7231 0.7447 0.7435 0.7399 0.7506DVPE psi 6.95 9.10 12.76 7.30 8.79 13.30 8.47Oxygenates--D4815MTBE vol % 0.00 0.00 0.00 0.00 0.00 0.00 0.00ETBE vol % 0.00 0.00 0.00 0.00 0.00 0.00 0.00EtOH vol % 0.00 0.00 0.00 9.54 9.42 9.03 20.38Oxygen wt % 0.00 0.00 0.00 3.53 3.49 3.36 7.49HCCompositionAromatics vol % 22.1 23.4 24.2 24.4 23.6 22.5 21.5Olefins vol % 8.0 9.6 9.5 8.8 9.6 9.6 10.9Saturates vol % 70.0 67.1 66.4 57.3 57.5 59.0 46.8D86DistillationIBP°F 99.9 88.8 82.0 104.0 97.2 83.7 103.310%°F 142.4 122.4 106.4 133.0 125.1 107.9 131.250%°F 197.9 191.0 189.1 195.0 189.8 165.4 159.690%°F 313.6 316.5 316.3 317.0 319.0 322.1 313.7EP°F 361.0 353.7 353.7 360.0 357.2 352.4 342.0Recovery vol % 97.8 97.6 96.6 97.8 97.9 96.7 98.3Residue vol % 1.3 1.6 1.3 1.0 1.1 1.4 1.1Loss vol % 1.0 0.8 2.1 1.2 1.0 1.7 0.7Drivability Index - 1120.7 1073.2 1043.2 1101.5 1075.9 979.9 989.1-14-Table 3-5Additional Fuel Properties (from Haltermann)Inspection Units Fuel 6 Fuel 3 Fuel5 Fuel 7 Fuel 1 Fuel 2 Fuel 4DVPE psi 6.95 9.10 12.76 7.30 8.79 13.30 8.47EtOH vol % 0.00 0.00 0.00 9.54 9.42 9.03 20.38Sulfur Content ppm 29 28 26 27 29 27 27Benzene vol % 0.90 1.00 1.00 1.00 1.00 0.98 0.96Research OctaneNumber93.2 94.4 94.6 94.0 92.9 94 94.6Motor OctaneNumber83.8 84.5 83.5 83.8 84.1 83.4 83.4(R+M)/2 88.5 89.5 89.0 88.9 88.5 88.7 89.0Benzene vol % 0.89 1.05 1.05 1.06 1.10 0.94 0.97C/H Ratio 6.200 6.196 6.170 6.092 6.106 6.143 5.835Net Heat ofCombustionbtu/lb 18,703 18,733 18,758 18,016 17,973 18,000 17,160Oxygen wt.% 0.008 0 0 3.396 3.609 3.488 7.733C+Hwt. % 99.99 100.00 100.00 96.60 96.39 96.51 92.27Hwt. % 13.89 13.90 13.95 13.62 13.56 13.51 13.50Cwt. % 86.10 86.10 86.05 82.98 82.83 83.00 78.77Net Heat ofCombustion D3338Btu/lb 18,573 18,592 18,580 18,514 18,516 18,521 18,513

### -15- Fuels were produced at three vapor pressu re levels (7.0, 9.0, and 13.0 psi) with three levels of ethanol (0%, 10%, and 20%). The E0 and E10 fuels were produced at all three vapor pressure levels. The E20 fuel was produced only at the 9.0 psi level.

Tests were performed at two temperatures ( 50° and 75°F) with each of the 9.0 psi and 13.0 psi fuels. The 7.0 psi fuels were tested only at 75°F. Figure 3-1 summarizes the combinations included in the test program.

Figure 3-1 Fuel Ethanol, Vapor Pressure, and Temperature Combinations Tested

### 50°F 75°F

E0 E10 E20 7.0 psi 9.0 psi 13.0 psi R V P Temperature

Ethanol

### -16- 

## 4. DATA ANALYSIS

4.1 Overview of Experimental Design

As was shown in Figure 3-1, the test pr ogram included 12 combinations of RVP (3 levels), ethanol content (3 le vels), and ambient temperature (2 levels). The design is unbalanced because only 12 of the possible 18 combinations of three variables were tested.

To obtain the greatest insight into the effects of RVP, oxygenate, and ambient temperature, the analysis in this section considers the dataset as if it involved the four individual experiments outlined below.

 An experiment on the effect of oxygen ate (ethanol content) conducted at a temperature of 75°F and at RVP 9. This experiment consists of the three test points E0, E10, and E20 in the background plane of the experimental matrix shown in Figure 3-1 at RVP 9. The emissi ons effect of varying oxygenate levels can be directly observed in this subset of the program test data.

 An experiment on the effect of low RV P at FTP conditions of 75°F. This experiment consists of the five test points in the background plane spanning E0, E10, and E20, and RVP 7 and 9 fuels. This experiment combines the effect of RVP 7 fuel (compared to a baseline of RV P 9 fuel), with two non-zero levels of oxygenate. As a result, the oxygenate effect must be controlled for in order to observe the emissions effect of low RVP fuel.

 An experiment on the effects of high RVP at FTP conditions of 75°F. This experiment consists of th e five data points in the background plane spanning E0, E10, and E20, and RVP 9 and 13 fuels. Be cause this experiment also combines oxygenate with RVP effects, statistical c ontrols must be employed to observe the emissions effect of high RVP fuel.

 A final experiment on the effects of high RVP at an ambient temperature of 50°F. This experiment consists of the five da ta points in the foreground plane spanning E0, E10, and E20, and RVP 9 and 13 fuels. After appropriate controls for the effect of oxygenate at low temperature, the effect of RVP at lower ambient temperatures can be observed in this experiment.

### -17- The benefit of this approach is that the major trends in the data can be easily seen and understood without relying on complex statistical models to infer the trends. In addition, the only variable for which statistical control is required is that of added oxygen content in the experiments dealing with RVP effects. This control can be easily implemented in simple statistical models that are unlikely to risk misfitting the data. The results of the individual analyses are then combined in Section 5 in a complete statistical analysis of the data and the estimation of correction factor equations for use in the MOBILE model.



## 4.2 Vehicle Technology Groups

The first step in the data analysis involved dividing the test vehicles into four groups based on the sophistication of their emission control technology:

1. Group 1 – Test vehicles No. 1, No. 2, and N o. 3. This group includes the oldest vehicles, certified to Tier 1 exhaust e mission standards. Two of the vehicles (Nos. 1 and 3) were not cer tified to enhanced evaporativ e emission or to cold CO standards.

2. Group 2 – Test vehicles No. 4 through No. 8. These vehicles were certified to NLEV exhaust emission, enhanced evapora tive emission, and cold CO standards.

3. Group 3 – Test vehicles Nos. 9, 10, and 13. This group consists of three vehicles certified to Tier 2 exhaust emission, enhanced evapora tive emission, and cold CO standards.

4. Group 4 – Test vehicles Nos. 11, 12, 14, and 15. This group consists of four vehicles certified to Tier 2 exhaust, n ear-zero evaporative emission, and cold CO standards.

In addition to the above, all of the vehicles in Groups 2 through 4 were equipped with onboard refueling vapor recovery systems.

The average FTP composite and bag emission rates by technology group are shown in Table 4-1.

Many of the vehicles in Groups 3 and 4 had emission levels, particularly for Bag 3, that were reported as zero because they fell below the minimum detectable levels of the emission analyzers when recorded to two decimal places. In order to include these data in the statistical analysis where logarithmic models were used for the dependent emission variable, a de minimus emission level of one-half of th e smallest non-zero measurement recorded for the pollutant was substituted for zero readings. At such low levels, the difference in logarithms of emissions can be subject to large fluctuations due to small values in the denominator. Thus, it should come as no surprise that estimating emission effects with high statistical confidence is sometimes problematic for these vehicles.

### -18- Table 4-1 Average Emission Rates by Technology Group (g/mile) (At 75°F, RVP = 9 psi, E0 fuel) Group 1 Group 2 Group 3 Group 4
NMHC CO NOx NMHC CO NOx NMHC CO NOx NMHC CO NOx

FTP 0.39 4.88 0.94 0.08 1.31 0.17 0.07 0.68 0.05 0.04 0.23 0.05 Bag 1 0.89 9.13 1.56 0.27 2.97 0.47 0.22 2.37 0.18 0.14 1.03 0.13 Bag 2 0.21 1.56 0.56 0.03 0.83 0.05 0.04 0.26 0.01 0.02 0.01 0.03 Bag 3 0.34 0.89 1.19 0.04 0.96 0.18 0.03 0.19 0.02 0.02 0.06 0.04



## 4.3 Test Fuels

As shown previously in Table 3-4, the T 50 temperatures for Fuels 2 and 4 differed markedly from those of the other test fuels. The other test fuels were controlled to have T50 values within the range 189°F to 198°F, while Fuels 2 and 4 had T50 values 24°F and 30°F below this range, respectively. Further, review of Summer and Winter Alliance of Automobile Manufacturers (AAM) Fuel Survey Data indicated that the T50 values of these fuels were substantially lower than the lowest values observed in commercial California gasolines. This raised a concern in light of the findings of the CRC E-67 study * 

### regarding emission impacts associated with T50 itself and with interactions between T50 and ethanol content.

In regard to T50 and ethanol content, the CRC E-67 study observed that ethanol content and T50 interacted in such a way that, at high levels of T50 (above 220°F), raising ethanol content to high levels was associated with increased CO emissions, an effect not seen at lower T50 levels. However, the high T50 level in the CRC E-67 study was well above the values in the test fuels for this project. In addition, the CRC E-67 study noted the presence of diminishing returns in the overall effect of ethanol content on CO emissions, such that the reduction in CO e missions due to oxygenation was primarily observed at low to mid levels, with little or no incremental benefit observed at high levels. This finding guided the conduct of this analysis and led to the characterization of a non-linear oxygenate effect for CO emissions.

In regard to the representativeness of Fu els 2 and 4, a Principal Components Analysis (PCA) was conducted on the fuel property data to gain insight on whether the low T50 values were anomalies or merely represented blending effects associated with meeting the experimental targets for RVP. PCA is a useful tool in many real-world problems

* Durbin, T.D., et al., “Effects of Ethanol and Volatility Parameters on Exhaust Emissions,” CRC Project No. E-67. College of Engineering – Center for Environmental Research and Technology, University of California, Riverside. January 2006.

### -19- where variables display a high degree of correlation among themselves. When the correlations are inherent—i.e., result from th e underlying physical reality—PCA can yield valuable insight to the causal factors at work in the data. PCA decomposes the correlation matrix describing the linear relationships among the variables into eigenvectors that represent the distinct patterns by which the variables covary in the data. The vectors themselves form an orthog onal basis and provide an independent (uncorrelated) set of va riables that can be used as an a lternative expression of the data. What is usually seen in PCA is that most of the variance in the data is explained by a small subset of eigenvectors, so that a redu ction in the dimensionality of the problem is achieved. It is not uncommon for 3 to 5 vector variables to represent 90% or more of the variation present in a dataset that contains 10 or more variables.

In this case, PCA revealed four primary eigenvectors that represent 96% of the variation in the fuels. Vectors 1 and 2 represent the blending methods used to form the experimental fuels and can be explained as follows:

 Vector 1 (49% of the variation in fuels) : An oxygenation index representing the blending of EtOH along with associated effects, including a tendency to increase RVP. This blending strategy appears to substitute aromatics and olefins for saturates in oxygenated fuels, possibly as a strategy to offset the direct RVP effect of added EtOH and to main tain target RVP levels.

 Vector 2 (27% of the variation in fuels) : An RVP index representing the reformulation of the base fuel to meet varying RVP targets, including a tendency for increased RVP to be associated with lower specific gravities and lower T10 distillation points. This blending strategy appears to raise RVP primarily by selecting lighter components within each of the hydrocarbon classes, so that the overall mix of aromatics, olefins, and saturates is relatively unchanged.

Together, Vector 1 and 2 account for 76% of the total variation in fuels. The two additional eigenvectors (Vectors 3 and 4) appear to represent final blending steps taken to control research octane number (RON) and motor octane number (MON), respectively, to near-constant levels.

Figure 4-1 diagrams the relationships between RVP and oxygen content in the experimental fuels as revealed by PCA. In the figure, each experimental fuel has been scored * 

### to determine the extent to which it expresses the characteristics described by Vectors 1 and 2. A shift in th e base RVP level is seen as a movement predominantly up and to the right on the formulation diagram, as seen between Fuels 3 and 5. A change in

* The scoring process is similar to computation of an index value from known properties to assess a characteristic in the absence of direct measurement. As an example, Diesel fuel can be scored for cetane quality using the ASTM cetane index method as an alternative to the actual measurement of cetane in a test engine.

### -20- Figure 4-1 Experimental Fuel Formulation for RVP and Oxygen Content

Fuel 1: E10 RVP 9 Fuel 2: E10 RVP 13

Fuel 3: E0 RVP 9

Fuel 4: E20 RVP 9

Fuel 5: E0 RVP 13

Fuel 6: E0 RVP 7 Fuel 7: E10 RVP 7

-3.0 -2.0 -1.0 0.0 1.0 2.0 3.0

-4.0 -3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 4.0Vector 2 Score: RVP Index

Vector 1 Score: Oxygenation Index Oxygenation

Oxygenation

Oxygenation Summer v.

Winter RVP Change



### the oxygenation level is seen as a movement down and predominantly to the right, as seen between Fuels 3, 1, and 4. *



### In this diagram, neither Fuel 2 (RVP 13) nor Fuel 4 (RVP 9) appears to be anomalous, in that each creates nearly parallel fuel reformulation lines representing the blending to increase oxygenation. What is distinctive is that Fuels 2 and 4 are the rightmost fuels in the diagram, and most strongly express the fu el reformulation represented by Vector 1. This vector represents not only fuel oxygen content, but also associated changes in the hydrocarbon composition of fuels with resu lting effects on specific gravity and the distillation curve. Vector 1 is strongly corr elated with T50 (r = -0.89), and it should be no surprise that Fuels 2 and 4, with the high est Vector 1 scores, have the lowest T50 values.

Whether the two fuels in question are fully representative of gasolines in the market, we conclude that they are logical outcomes of the blending strategies used to create the experimental fuels and should be retained in the analysis. A larger issue is whether the T50 effects that occurred in the blending of Fuels 2 and 4 are representative of those observed in commercial gasolines at these RVP and oxygenate levels. There is, unfortunately, no definitive answer to this question, particularly for E20 blends where standardized fuel specifications do not exist.

* Fuels 6 and 7, which are not of direct concern here as their T50 values do not differ significantly, also show that oxygenation leads predominantly to movement down and to the right, while RVP reductions lead to movement down and to the left

.

### -21- The depression of T50 in Fuels 2 and 4 below the range of the other fuels has significant consequences for the interpretati on of the data generated in this project. If the lower T50 level of these fuels leads to an emission e ffect in its own right, then Fuels 2 and 4 confound that T50 effect to some degree with effects of oxygenate content and RVP. Confounding means that two or more variables are correlated to such an extent that it becomes difficult or impossible to separa te their individual contributions.

In this dataset, the consequen ces of confounding are as follows:

 Fuel 4 is the only test fuel containing more than 10% ethanol. If Fuel 4 were removed from the dataset, the analysis woul d necessarily be restricted to the range of E0 to E10. By retaining Fuel 4, the analysis can assess whether the emissions effect due to the higher oxygen content is in proportion to that observed at lower levels, but it cannot determine whether the resu lt is due to higher oxygen levels or to a much lower T50 or to some combination of the two effects.

 Fuel 2 is one of two test fuels at RVP 13 and the only such test fuel that also contained oxygen. Removing Fuel 2 from the dataset would leave the analysis dependent on only one test fuel for the determination of RV P effects and would make it impossible to test whether there was an interaction between increased RVP and oxygen content. By retaining Fuel 4, the analysis can test for the presence of an interaction be tween RVP and oxygen content, although it cannot determine the extent to which such an interaction is caused by RVP and Oxygen or by T50 or by a combination of the variables.

In addition, estimates of the effect of RV P itself and in interaction with ambient temperature will be partially confounded by emissions effects caused by T50. Such partial confounding is termed aliasing and occurs in regression analysis when the coefficient estimated for a variable such as RVP is changed in value by the inclusion of effects actually caused by another variable (such as T50), which is correlated with the predictor but not included in the regression m odel. The presence of aliasing means that the coefficient does not estimate the effect associated with the predictor alone. As a result, the coefficient estimate is biased w ith respect to the true (but unknown) value. The depression of T50 values in two of th e test fuels poses a major problem in the analysis due to the confounding with design effects and the potential for aliasing to change estimated coefficient values.

It was determined that there was no potential for separating the imbedded T50 effect by the application of statistical controls. This is because T50 is exactly confounded with the high oxygenation level (E20) and with the interaction between RV P and oxygen content at the E10 level. * 

### Instead, the analysis was conducted twice in order to attempt to assess the import of the T50 effects.

* The confounded terms are the quadratic term in OxPct, which represents the extent to which emissions of the E20 fuel differ from what would be expected from extrapolating the E10 effect to E20, and the term RVP · OxPct.

### -22-  The first (and primary) analysis used data for all of the test fuels and regression terms formed from the variables T, RVP, OxPct, and their two-way interactions. This analysis contains an embedded T50 effect of the kind introduced by Fuels 2 and 4 and ascribes those effects to term s involving RVP and OxPct. Its results can be used reliably and without bias to the extent that T50 depression is generally observed in fuels blended to these RVP and oxygenate levels.

 A second (sensitivity) analysis in which the two terms that are exactly confounded by T50 are dropped from consideration and replaced by a term measuring the T50 depression below a reference level of 190°F. This analysis contains an explicit T50 effect, but it will ascribe to T50 any incremental effects that are related to the E20 oxygen level or to the interaction between RVP and oxygen content (at the E10 level). Its results serve to bracket quantitatively the limitations of the first analysis and of predictions based on it. It may prove possible to use the results of this sensitivity analysis to adjust predictions (at least approximately) if T50 depression does not occur in fuels ble nded to the RVP and oxygenate levels reflected in Fuels 2 and 4.



## 4.4 Statistical Analysis Methodology

As discussed above, the test pr ogram data can be viewed as a series of experiments in which selected fuels and tests examine the response of the test vehicles to changes in fuel oxygen content and RVP at test temperatures of 75°F and 50°F. The analyses of these individual experiments are presented below. In general, the methodology involved fitting simple statistical models to subsets of the data to estimate the effects of oxygenation and RVP on CO emissions. Only CO emissions are examined in this stage, because the objective of the test program was to evaluate oxygenate, RVP, and temperature effects on CO emissions. Questions related to the presence and magnitude of emission effects by FTP phase and by vehicle technology gr oup are considered, and estimated emission changes are presented in both tabular and graphical form.

Based on the trends established in these individual analyses, an overall model is formulated for emission adjustment factors as a function of ambient temperature, RVP, and fuel oxygen content. A complete statistical analysis, including the development of the new correction factor equations for CO , NOx, and HC emissions by FTP phase, is presented in Section 5.

The analysis reported here was conducted using the general linear models procedure (PROC GLM) of the Statistical Analysis System (SAS) to fit general linear models involving temperature, RVP, and oxygen content to exhaust emissions. In some instances, an alternative SAS regression package (PROC REG) was used when it was desired to produce datasets containing residuals, predicted values, and confidence limits. Conventional regression techniques were used to fit and evaluate models in order to test the statistical significance of differing formulations and to conduct tests on whether terms

### -23- differed significantly by technology group or vehicle type. The logarithm of exhaust emissions was used in all cases as the dependent variable.

Because the purpose of the analysis is to meas ure the response of vehicles to temperature, RVP, and oxygen content, a statistical t echnique known as absorption was used to remove the effect of varying emissions levels by vehicle. This t echnique is numerically equivalent to including dummy variables in the model to represent the mean emission levels of N-1 vehicles, but it is generally eas ier to specify such models using absorption. If emissions data on vehicles with varying e mission levels are pooled for analysis without absorption or the use of dummy variables, th e estimated response coefficients will often be dominated by the vehicles with the highes t emissions levels. That is, in cases where the response is proportional to a base emission level, high emission vehicles will tend to show large responses and will create an upward bias in the response co efficients that are estimated.

Unlike the fitting of dummy variables, absorption removes the effect of varying emission levels by first normalizing all data (both dependent and independent variables) to remove the corresponding mean values for each vehicle. That is, log emissions ln(E) is replaced by the logarithm of the emissions ratio ln(E/E 0 

### ) relative to the mean emissions level E 0 

### for the vehicle, ambient temperature is replaced by the deviation of temperature from the average temperature for each vehicle, and RV P and oxygen content are similarly replaced by their deviations from the mean. As a result, the data are cast in the form of deviations from a reference point for each vehicle that has been removed from the data. When the resulting normalized data are pooled in the anal ysis, each vehicle is given equal weight in estimating the response coefficients. This choice of reference point (the mean values) is mathematically equivalent to any other choi ce of reference point, such as the vehicle emission level at FTP conditions.

The varying emission levels of the individual ve hicles are by far the largest contributor to the total variance in the data. PROC GLM c ounts this contribution to the sum of squares reduction in computing the regression R 2 

### statistic, as does PROC REG count the sum of squares reduction due to dummy variables for ve hicles. As a result, all of the regression models fit in this analysis approach or exceed R 2 

### values of 0.90. R 2 

### is at best a simplistic measure of goodness-of-fit in regression m odeling and, in this case, where all R 2 

### values are very high, it is of little utility. As a result, R 2 

### statistics are not reported in the discussion of the statistical results.



## 4.5 Analysis of Oxygenate E ffects on CO Emissions

The starting point for the analysis is the examination of oxygenate effects on CO emissions. Tests at FTP conditions of 75° F and RVP 9 on Fuels 3, 1, and 4 (E0, E10, and E20, respectively) were selected to isolate th e effect of oxygenation from changes in RVP or ambient temperature. While the fuels are described by their nominal ethanol content, the actual measured oxygen content is used as the independent variable. Values given as “percent CO reductions per percent” refer to percent oxygen content.

### -24- For reference, the MOBILE6.2 adjustment factor s for Tier 1 and later vehicles use these values:

 Normal emitters: no effect from oxygenate.

 High emitters: -5.3 percent per percent oxygen.

None of the vehicles in this project would be classified as high emitters (defined as CO emissions exceeding 3 times the 50,000 mile CO st andard), with Vehicle 2 being closest to a high emitter at 2 times the 50,000 mile sta ndard. As a result, the analysis can determine the emissions effect of oxygenation for normal emitters only.

The analysis of oxygenate effects uses a log emissions model to estimate the sensitivity of CO emissions to oxygen content by vehi cle technology group and FTP test phase. The regression model is of the mathematical form:

ln[CO · (OxPct)/CO 0 

### ] = C 1 

### · OxPct (Eq. 4-1)

where OxPct is the oxygen content stated as a weight percent (not decimal fraction). The model assumes a linear response of CO emissions to oxygen content, and CO 0 

### is the CO emissions at FTP conditions of 75°F, RVP 9, a nd E0. The model is fit in log space as a simple equation of the form Y = A + B · Ox Pct, and the reference emissions level CO 0 

### is computed from the regression intercept A.

The results of the analysis are summarized in Table 4-2, which shows the estimated coefficient C 1 

### , along with standard errors and si gnificance levels, and two measures of the oxygenate effect:

 The estimated reduction in CO emissions at 3.7 percent oxygen content typical of E10 gasoline; and

 The estimated percent change in CO emissions per percent oxygen content.

Estimates reported with pr ob>|t| of 0.05 or less are statistical ly significant at a 95 percent confidence level or better, while estimates with prob>|t| in the range 0.10 to 0.05 can be accepted as being statistically significant at reduced confidence levels (in the range of 90 to 95 percent).

As seen clearly in Table 4-2, an oxygenate ef fect is present in all technology groups and FTP phases, with CO emissions declining with increasing oxygen content. The magnitude of the effect is also relatively consistent (within the error of the estimates) across technology groups and FT P phases, with CO emissions being reduced in most instances by 5 to 9% per percent oxygen c ontent. The observed oxygenate effect is

### -25- Table 4-2 Effect of Fuel Oxygen Content on CO Emissions (FTP Conditions of 75°F, RVP 9)

Vehicle Group N FTP Phase lnCO Model (E0, E10, E20) CO Benefit For E10 Percent CO Change per
% 

### Oxygen C 1 Std Err Prob >|t|

All 15 Composite -0.072 0.012 0.0001 -23% -6% Bag 1 -0.054 0.009 0.0001 -18% -5% Bag 2 -0.198 0.052 0.0003 -52% -14% Bag 3 -0.084 0.042 0.0497 -27% -7%

1 3 Composite -0.079 0.022 0.0037 -25% -7% Bag 1 -0.064 0.014 0.0006 -21% -6% Bag 2 -0.117 0.027 0.0012 -35% -10% Bag 3 -0.049 0.032 0.1608 -16% -4%

2 5 Composite -0.076 0.024 0.0054 -25% -7% Bag 1 -0.044 0.011 0.0010 -15% -4% Bag 2 -0.248 0.102 0.0244 -60% -16% Bag 3 -0.099 0.040 0.0218 -31% -8%

3 3 Composite -0.047 0.008 0.0001 -16% -4% Bag 1 -0.043 0.012 0.0035 -15% -4% Bag 2 -0.103 0.052 0.0747 -32% -9% Bag 3 -0.065 0.045 0.1796 -21% -6%

4 4 Composite -0.080 0.029 0.0137 -26% -7% Bag 1 -0.068 0.027 0.0232 -22% -6% Bag 2 -0.267 0.145 0.0828 -63% -17% Bag 3 -0.107 0.148 0.4795 -33% -9%



### generally as large as, or larger than, the -5.3% per percent oxygen effect used in MOBILE6.2 for high emitters, and it obviously exceeds the MOBILE6.2 assumption of no effect for normal emitters.

The oxygenate effect is statistically significant for the FTP Composite, Bag 1, and Bag 2 tests, both overall (all vehicles ) and in all technology groups, in spite of low CO emission levels for Groups 1 and 2 and very low CO emission levels for Groups 3 and 4. For Bag 3, the effect is statistically significant ov erall and for Group 2 vehicles. The effect appears to be present in other technology groups, but fails the test of statistical significance in those groups at conventionally accepted levels of st atistical significance.

Figure 4-2 presents bar charts by FTP phase and vehicle technology group that are similarly scaled on the vertical axis to facilitate a visual comparison of the trends. The bars are shown below the zero line to emphasi ze that the oxygenate effect reduces CO emissions. Error bars (vertical lin es) are shown in the graphs as  1 standard errors ( σ );

### -26- the 95 percent confidence limits would be twice as wide. An approximate test of the significance of observed differences can be based on these 1 σ error bars: two estimates are not significantly different if their 1 σ error bars overlap.

As seen in Figure 4-2, the oxygenate effect is smaller (in percentage terms) in Bag 1 than in Bag 2. The Bag 1 to Bag 2 difference is statistically significant, and this is true in all four technology groups. The effect in Bag 3 ap pears to be intermediate in size between Bags 1 and 2, but the error bars are generally large enough that it is not statistically different from the Bag 1 effect.

The oxygenate effect is very consistent across technology groups. Depending on the FTP phase, the graphs may suggest that the Group 4 vehicles have a somewhat smaller effectthan other technology groups. However, formal tests for the existence of technologyrelated differences find no evidence that the oxygenate effect (by Phase) differs among the four primary technology groups, among exha ust or evaporative technology groups, or between passenger cars (PC) and light-duty tr ucks (LDT). The oxygenate effect appears to be homogenous with respect to vehicle tec hnology, in spite of the progressively lower levels of CO emissions of newer vehicles.

The key conclusions of this analysis are that the data indicate clearly a substantial oxygenate effect in late-model motor vehicles (at least at the FTP conditions of 75°F and RVP 9), and that its magnitude appears to be consistent across the vehicle technology groups. The oxygenate effect varies by FTP phase, ranging from about -5% per percent oxygen in Bag 1, to -14% per percent oxygen in Bag 2, and to -7% per percent oxygen in Bag 3. As will be seen in the following sections, the emissions data obtained with the oxygenated fuels used in the RVP testing at both 50°F and 75°F support these conclusions.

### -27- Figure 4-2 Oxygenate Effect by FTP Phase and Technology for RVP 9 Fuels at 75°F

-40% -35% -30% -25% -20% -15% -10% -5% 0% All Group 1 Group 2 Group 3 Group 4Oxygen Benefit (Percent per %) FTP Composite

-40% -35% -30% -25% -20% -15% -10% -5% 0% All Group 1 Group 2 Group 3 Group 4Oxygen Benefit (Percent per %) FTP Bag 1

-40% -35% -30% -25% -20% -15% -10% -5% 0% All Group 1 Group 2 Group 3 Group 4Oxygen Benefit (Percent per %) FTP Bag 2

-40% -35% -30% -25% -20% -15% -10% -5% 0% All Group 1 Group 2 Group 3 Group 4Oxygen Benefit (Percent per %) FTP Bag 3

### -28- 

## 4.6 Analysis of RVP Effects Between 7 and 9 psi at 75°F

A previous study of RVP effects on CO emissions based on CRC research * 

### using vehicle certification data concluded, “Fuel volatility increases between 7 RVP and 9 RVP have little effect on CO emissions at 75°F. This is consistent with the MOBILE6 model, because the MOBILE model predicts CO increases only at volatilities above 9 RVP.” As suggested by Figure 4-3, and supported by the an alysis in this section, the data from this project are consistent with the conclusion of th e earlier study. It is possible that a small CO emissions increase occurs between 7 and 9 RVP, but the magnitude of such increase (if it exists) is small compared to the normal variation in the test data. The data from this project show no statistically significant evid ence that CO emissions increase between 7 and 9 RVP.

Figure 4-3 Example of CO Emissions Trends with RVP at 75°F FTP Composite CO (All Vehicles)

0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50

5 7 9 11 13 15 RVPCO Emissions (gm/mi)

E0 E10 E20

Note: The error bars are  1 standard error ranges.



### An analysis was conducted of CO emissi on changes between 7 and 9 RVP using five fuels tested at 75°F, including Fuels 6 (E0) and 7 (E10) and Fuels 3 (E0), 1 (E10), and 4 (E20). The analysis uses a log emissions model to estimate the sensitivity of CO emissions to RVP changes by vehicle tec hnology group and FTP test phase at 75°F:

ln[CO · (RVP)/CO 0 

### ] = C RVP 

### · (RVP – 9) + C 1 

### · OxPct (Eq. 4-2)

* Examination of Temper ature and RVP Effects on CO Emissi ons in EPA’s Certification Database . Final Report CRC Project No. E-74a. Prepared by Air Improvement Research, Inc., Novi, Michigan. April 2005.

### -29- where RVP is in units of psi and OxPct is th e fuel oxygen content as a weight percent (not decimal fraction). * 

### CO 0 

### is the CO emissions at FTP conditions of 75°F, RVP 9, and E0. This model assumes a linear response of CO emissions to variation in RVP at a constant ambient temperature of 75°F. The actual measured RVP value is used as the independent variable, not the nominal RVP le vel planned in the ex perimental design. The OxPct term is included as a control for the oxygenate effect in three of the fuels. While the oxygenate effects are displayed graphically, the estimated C 1 

### coefficients are not tabulated.

Table 4-3 summarizes the effect of increasing RVP from 7 to 9 at 75°F and E0. In general, the analysis is unable to detect a meaningful effect on CO emissions with an acceptable degree of statistical confidence. For Groups 1 and 2, the analysis estimates a small CO emission decrease at 7 RVP in some cases, ranging from reductions of 7 to perhaps as much 20%. In other cases, however, the analysis estimates a CO emission increase, and none of the estimates reach a c onventionally accepted level of statistical significance. For Groups 1 and 2, only two of the estimates could be considered weakly

Table 4-3 Effect of Low Gasoline RVP on CO Emissions (FTP Conditions of 75°F)

Vehicle Group N FTP Phase lnCO Model (RVP 7-9, E0, E10, E20) CO Benefit For RVP 7

Gasoline C RVP Std Err Prob >|t|

All 15 Composite 0.018 0.027 0.51 7% Bag 1 -0.019 0.024 0.41 -7% Bag 2 0.321 0.145 0.03 262% Bag 3 -0.110 0.122 0.37 -35%

1 3 Composite -0.017 0.043 0.70 -7% Bag 1 -0.062 0.033 0.09 -22% Bag 2 0.071 0.088 0.44 33% Bag 3 -0.051 0.038 0.22 -18%

2 5 Composite 0.086 0.046 0.08 41% Bag 1 0.000 0.030 0.99 0% Bag 2 0.756 0.343 0.04 1961% Bag 3 0.085 0.082 0.31 41%

3 3 Composite 0.000 0.029 0.99 not measurable Bag 1 0.000 0.032 0.99 not measurable Bag 2 0.066 0.129 0.62 not measurable Bag 3 -0.007 0.123 0.96 not measurable

4 4 Composite -0.027 0.078 0.73 not measurable Bag 1 -0.026 0.075 0.73 not measurable Bag 2 0.157 0.311 0.62 not measurable Bag 3 -0.474 0.443 0.30 not measurable

* As before, the model is fit in log space as a simple equation of the form Y = A + B · OxPct, and the reference emissions level CO 0 is computed from the regression intercept A.

### -30- significant (Group 1 Bag 1, and Group 2 Composite). For Groups 3 and 4, the confidence level of the estimates is so low that the CO benefit is reported as being not measurable. Only the estimate for Group 2 Bag 2 reaches the 95% confidence level in significance, and this result gives an implausibly large emissions effect. (This result is also responsible for the Bag 2 estimate for a ll vehicles showing a comparably large and implausible emissions effect.)

A review of the individual test data strong ly suggests that one vehicle is primarily responsible for this outcome, although no fo rmal outlier test was performed given the exploratory nature of the analysis in this section. Vehicle 7 produced CO emissions of 0.82 g/mile when tested at FTP conditions (RVP 9, E0) and 0.09 g/mile and 0.00 g/mile when tested on E10 and E20 fuels at 9 RVP. Both of its tests at 7 RVP reported CO emissions of 0.00 g/mile. As a result, the change from 7 to 9 to RVP (at zero oxygen content) is associated with a 100% reducti on in CO emissions. Other vehicles showed CO emission changes ranging fro m -18% to +19% in the same circumstances. It is unknown whether the specific test results for Ve hicle 7 represent a marked sensitivity to RVP (and fuel oxygenation) or reflect a change in vehicle condition after the baseline test on Fuel 3. However, it is clear that the apparent response to reduced RVP is not characteristic of the other vehicles. The implausible result for Group 2 Bag 2 has been discounted for the purposes of this section, but Ve hicle 7 has been retained in the dataset. In the analysis of the following section, Vehi cle 7 is shown to have a response to RVP 7 fuel that is both statistically significant and different from the responses of other vehicles, which fail to reach the threshold of statistically significance.

In all other respects, there is no evidence in the dataset that RVP changes between 7 and 9 RVP have statistically significant effects on CO emissions at 75°F, although the presence of an RVP effect smaller than th e normal test variation cannot be ruled out. This conclusion is true whether vehicles are pooled to increase the sample size for analysis or divided into technologically hom ogenous groups. These trends are illustrated in the bar charts of Figure 4-4, which is indi vidually scaled on the vertical axis to display the estimates for each FTP phase. Error bars (vertical lines) represent  1 standard error ( σ ); the 95% confidence limit of the estimates would be twice as wide. Two estimates are not significantly different if their 1 σ error bars overlap (approximately).

On the other hand, the dataset indicates the pr esence of an oxygenate effect for 7 and 9 RVP fuels in each FTP phase and vehicle technology group. The observed oxygenate effect at 7 RVP varies in magnitude by FT P phase and is presen t across all technology groups (if not always statistical ly significant). These trends are illustrated in the bar charts of Figure 4-5, which is scaled on the vertical axis to facilitate a visual comparison of the trends. Error bars (vertical lines) are shown as  1 standard error ( σ ); the 95 percent confidence limit of the estimates would be twice as wide. Two estimates are not significantly different if their 1 σ error bars overlap (approximately).

### -31- Figure 4-4 7 RVP Effect by FTP Phase and Technology at 75°F Compared to 9 RVP Fuels

-15% -10% -5% 0% 5% 10% 15%

All Group 1 Group 2 Group 3 Group 4RVP Effect (Percent per psi) FTP Composite

-12% -10% -8% -6% -4% -2% 0% 2% 4% 6%

All Group 1 Group 2 Group 3 Group 4RVP Effect (Percent per psi) FTP Bag 1

-50% -40% -30% -20% -10%

0% 10% 20%

All Group 1 Group 2 Group 3 Group 4RVP Effect (Percent per psi) FTP Bag 3 -40% -20%

0% 20% 40% 60% 80% 100% 120% 140%

All Group 1 Group 2 Grpup 3 Group 4RVP Effect (Percent per psi) FTP Bag 2

### -32- Figure 4-5 Oxygenate Effect by FTP Phase and Technology for RVP 7 to 9 Fuels at 75°F

-25% -20% -15% -10% -5% 0% All Group 1 Group 2 Group 3 Group 4Oxygen Benefit (Percent per %) FTP Composite

-25% -20% -15% -10% -5% 0% All Group 1 Group 2 Group 3 Group 4Oxygen Benefit (Percent per %) FTP Bag 1

-25% -20% -15% -10% -5% 0% A ll Group 1 Group 2 Group 3 Group 4Oxygen Benefit (Percent per %) FTP Bag 3 -25% -20% -15% -10% -5% 0% All Group 1 Group 2 Grpup 3 Group 4Oxygen Benefit (Percent per %) FTP Bag 2

### -33- 

## 4.7 Analysis of the Effect of Increasing RVP from 9 psi to 13 psi at 75°F

Another RVP analysis was conducted at 75°F us ing the test data for the three Fuels 3, 1, and 4 (E0, E10, E20, respectively) at 9 RV P and the two Fuels 5 and 2 (E0 and E10, respectively) at 13 RVP. The analysis uses the log emissions model described previously to estimate the sensitivity of CO emissions to RVP changes by vehicle technology group and FTP test phase. The model is of the form:

ln[CO · (RVP)/CO 0 

### ] = C RVP 

### · (RVP – 9) + C 1 

### · OxPct (Eq. 4-3)

where RVP is in units of psi and OxPct is a wt percent oxygen content (not decimal fraction). * 

### CO 0 

### is again the CO emissions at FTP conditions of 75°F, 9 RVP, and E0. As before, the actual measured RVP value is used as the independent variable, and the OxPct term is included as a control for the oxygenate effect in three of the fuels.

The results of the analysis show that as RVP increases from 9 psi to 13 psi, increases in CO emissions are observed. In addition, the data again demonstrate the presence of a oxygenate effect in all FTP Phases and for all vehicle technology groups.

For reference, MOBILE6.2 CO uses the following factors to adjust CO emissions for RVP levels about 9 psi for vehi cles certified to Tier 1 a nd more stringent standards:

Bag 1: +4.2 percent per psi Bag 2: +30.0 percent per psi Bag 3: +26.1 percent per psi

Table 4-4 summarizes the results of the anal ysis. For Groups 1 and 2, increasing RVP from 9 to 13 at 75°F consistently increases CO emissions by amounts on the order of 5% per psi in Bag 1, 10 to 35% per psi in Bag 2, and 15 to 20% in Bag 3. These estimated RVP effects are comparable in magnitude to those assumed in MOBILE6.2 for Bag 1, but are somewhat smaller in magnitude than th e MOBILE6.2 effects for Bags 2 and 3. The RVP effects are statistically significant at the 95 percent confidence level (or better) for Group 1 vehicles, but are both smaller and of weaker significance for Group 2 vehicles.

For Groups 3 and 4, the estimated RVP effect is always smaller than for Groups 1 and 2 and is of inconsistent algebraic sign (positive and negative), with the one exception of the Bag 2 effect in Group 4. All of the estimated effects display such poor statistical significance that they are reported as not m easurable. The best level of significance achieved in any bag for Groups 3 and 4 could still occur by chance with a probability of nearly 1 in 3 (28%). No one vehicle (or subset of vehicles) appears to be responsible for this outcome. Instead, the variance in the data is simply large enough that, at the low emission levels of these vehicles, there is no statistical significance to the estimated effects.

* As before, the model is fit in log space as a simple equation of the form Y = A + B · OxPct, and the reference emissions level CO 0 is computed from the regression intercept A.

### -34- Table 4-4 Effect of High Gasoline RVP on CO Emissions (FTP Conditions of 75°F)

Vehicle Group N FTP Phase lnCO Model (RVP 9-13, E0-E20) CO Impact of 13 RVP Gasoline Percent CO Change per Psi C RVP Std Err Prob >|t|

All 15 Composite 0.062 0.015 0.000 28% 6.4% Bag 1 0.024 0.012 0.054 10% 2.5% Bag 2 0.146 0.073 0.052 79% 15.7% Bag 3 0.053 0.061 0.385 24% 5.5%

1 3 Composite 0.080 0.021 0.003 38% 8.3% Bag 1 0.041 0.016 0.026 18% 4.2% Bag 2 0.085 0.031 0.021 41% 8.9% Bag 3 0.113 0.033 0.007 57% 12.0%

2 5 Composite 0.099 0.028 0.002 49% 10.4% Bag 1 0.017 0.016 0.320 7% 1.7% Bag 2 0.221 0.141 0.134 142% 24.8% Bag 3 0.140 0.049 0.010 75% 15.0%

3 3 Composite 0.005 0.011 0.688 not measurable Bag 1 -0.006 0.018 0.725 not measurable Bag 2 0.035 0.078 0.662 not measurable Bag 3 -0.039 0.067 0.572 not measurable

4 4 Composite 0.046 0.041 0.280 not measurable Bag 1 0.044 0.039 0.272 not measurable Bag 2 0.180 0.209 0.403 not measurable Bag 3 -0.031 0.220 0.891 not measurable



### Figure 4-6 shows the trend in RVP effect s by FTP phase and technology group in the format used in prior sections to facilitate the visual comparison of trends by FTP phase and vehicle technology group. Error ba rs (vertical lines) are shown as  1 standard errors ( σ ); the 95 percent confidence limit of the estimates would be twice as wide. Two estimates are not significantly different if their 1 σ error bars overlap (approximately).

The key conclusions to draw for increasing RVP from 9 to 13 psi at 75°F are as follows:

 A statistically significant RVP effect ex ists in Groups 1 and 2. This is of comparable size (or perhaps somewhat smaller, depending on FTP phase) to the effect assumed in MOBILE6.2 An effect may not exist in Groups 3 and 4, or it may be too small to detect with acceptable statistical significance.

 For Groups 1 and 2, the RVP effect is smaller in Bag 1 than in Bag 2. The Bag 3 effect appears to be intermediate in magnitude, but may not be significantly different from the values in the other Phases.

### -35- Figure 4-6 Impacts of 13 RVP Fuel by FTP Phase and Vehicle Group at 75°F Relative to 9 RVP Fuel

0% 2% 4% 6% 8% 10% 12% 14%

All Group 1 Group 2 Group 3 Group 4RVP Effect (Percent per psi) FTP Composite

0% 1% 2% 3% 4% 5% 6% 7% 8%

All Group 1 Group 2 Group 3 Group 4RVP Effect (Percent per psi) FTP Bag 1

0% 2% 4% 6% 8% 10% 12% 14% 16% 18% 20%

All Group 1 Group 2 Group 3 Group 4RVP Effect (Percent per psi) FTP Bag 3 0% 5% 10% 15% 20% 25% 30% 35% 40%

All Group 1 Group 2 Group 3 Group 4RVP Effect (Percent per psi) FTP Bag2

### -36- Formal tests for differences by technology i ndicate that Groups 1 and 2 can be combined for the estimation of RVP effects. The formal tests find no evidence that RVP effects at 75°F differ by evaporative control technology or between PCs and LDTs for vehicles in Groups 1 and 2.

Figure 4-7 shows the effect of fuel oxygenation on CO emissions that was estimated in conjunction with the RVP effect. The sizes of the effect by FTP phase are similar (within the error bars of the data) to those seen in 9 RVP fuels in the prior analysis. Formal tests for whether the RVP effect varies by technol ogy indicate that no such differences can be detected, whether by exhaust or evaporative control technology or between PC and LDT.



## 4.8 Analysis of Impact of Increasing RVP from 9 psi to 13 psi at 50°F

The effect of RVP and oxygen content at 50°F was assessed using a regression model of the form found in Eq. 4-3. However, the CO 0 

### term in the equation is now measured relative to CO emissions at 50°F , 9 RVP, and E0. Put another way, the underlying effect of cold ambient temperature on CO emissions is incorporated in the baseline CO value.

Table 4-5 summarizes the results of the RVP analysis at 50°F. There is evidence that increasing RVP from 9 to 13 psi reduces CO emissions in Bag 1. This effect is highly significant when all vehicles are grouped together, and the RVP coefficient has a consistent (negative) sign in all technology groups, even when not statistically significant.

In the other FTP phases, increasing RVP fro m 9 to 13 at 50°F may have small upward effects on CO emissions, but the result is at be st of weak statistical significance. Groups 3 and 4 show directionally similar results, of similar or smaller magnitude, but the results fail to reach an acceptable level of statistical significance. An effect may well be present, but it may be difficult to detect at the low emission levels of these vehicles.

### -37- Figure 4-7 Oxygenate Effects by FTP Phase and Technology 9 to 13 RVP Fuels at 75°F

-40% -35% -30% -25% -20% -15% -10% -5% 0% All Group 1 Group 2 Group 3 Group 4Oxygen Benefit (Percent per %) FTP Composite

-40% -35% -30% -25% -20% -15% -10% -5% 0% A ll Group 1 Group 2 Group 3 Group 4Oxygen Benefit (Percent per %) FTP Bag 1

-40% -35% -30% -25% -20% -15% -10% -5% 0% All Group 1 Group 2 Group 3 Group 4Oxygen Benefit (Percent per %) FTP Bag 3 -40% -35% -30% -25% -20% -15% -10% -5% 0% All Group 1 Group 2 Group 3 Group 4Oxygen Benefit (Percent per %) FTP Bag 2

### -38- Table 4-5 Effect of High Gasoline RVP on CO Emissions (Cold-Ambient Temperature of 50°F)

Vehicle Group N FTP Phase lnCO Model (RVP 9-13, E0-E20) CO Impact of 13 RVP Gasoline Percent CO Change per psi C RVP Std Err Prob >|t|

All 15 Composite -0.026 0.016 0.107 -10% -2.6% Bag 1 -0.020 0.018 0.009 -8% -2.0% Bag 2 0.038 0.038 0.374 16% 3.9% Bag 3 0.032 0.072 0.663 13% 3.2%

1 3 Composite 0.004 0.024 0.873 2% 0.4% Bag 1 -0.008 0.023 0.732 -3% -0.8% Bag 2 0.075 0.034 0.050 35% 7.8% Bag 3 0.007 0.025 0.778 3% 0.7%

2 5 Composite -0.016 0.022 0.472 -6% -1.6% Bag 1 -0.070 0.018 0.001 -24% -6.7% Bag 2 0.043 0.065 0.519 19% 4.4% Bag 3 0.040 0.024 0.115 17% 4.0%

3 3 Composite -0.032 0.023 0.195 -12% -3.1% Bag 1 -0.048 0.027 0.104 -17% -4.7% Bag 2 0.036 0.053 0.503 16% 3.7% Bag 3 0.067 0.077 0.405 31% 6.9%

4 4 Composite -0.056 0.047 0.252 -20% -5.5% Bag 1 -0.074 0.056 0.209 -25% -7.1% Bag 2 0.005 0.135 0.971 2% 0.5% Bag 3 0.013 0.275 0.962 5% 1.3%



### Figure 4-8 shows the trend in RVP effect s by FTP phase and technology group. Error bars (vertical lines) are shown as  1 standard errors ( σ ); the 95 percent confidence limit of the estimates would be twice as wide. Two estimates are not significantly different if their 1 σ error bars overlap (approximately).

The key conclusions drawn from the RVP analysis at 50°F are as follows:

 There is clearly a reduction in Bag 1 CO emissions at low temperature resulting from increasing RVP to 13 psi. The effect appears to exist in all technology groups, although it cannot be estimated in th ree of them with acceptable statistical significance.

 There appears to be a consistent, but sm all, adverse effect on CO emissions in Bags 2 and 3, but it is too small to estimate with any degree of statistical significance using the 50°F subset of the data.

### -39- Figure 4-8 Effects of 13 RVP Fuel by FTP Phase and Technology at 50°F Relative to RVP 9 Fuels

FTP Composite

-12.0% -10.0% -8.0% -6.0% -4.0% -2.0% 0.0% 2.0% 4.0% All Group 1 Group 2 Group 3 Group 4RVP Effect (Percent per psi)

FTP Bag 2

0% 2% 4% 6% 8% 10% 12% 14% 16%

All Group 1 Group 2 Group 3 Group 4RVP Effect (Percent per psi)

FTP Bag 3

0% 5% 10% 15% 20% 25% 30% 35%

All Group 1 Group 2 Group 3 Group 4RVP Effect (Percent per psi) FTP Bag 1

-14% -12% -10% -8% -6% -4% -2% 0% 2% 4% All Group 1 Group 2 Group 3 Group 4RVP Effect (Percent per psi)

### -40- As noted previously, Section 5 presents the resu lts of a complete statistical analysis of the test data and uses the results of the analysis to estimate RVP correction equations as a function of ambient temperature; these correction equations account for the likely presence of a small RVP effect at 50°F.

Figure 4-9 shows the effect of fuel oxygenation on CO emissions that was estimated in conjunction with the RVP effect. The sizes of the effect by FTP phase are directionally consistent with those seen in previous sec tions, but of generally smaller magnitude at 50°F than at 75°F. The oxygenate effect again appears to be present and relatively consistent across all technology groups.

### -41- Figure 4-9 Oxygenate Effects by FTP Phase and Technology for 9 to 13 RVP Fuels at 50°F

-40% -35% -30% -25% -20% -15% -10% -5% 0% All Group 1 Group 2 Group 3 Group 4Oxygen Benefit (Percent per %) FTP Composite

-40% -35% -30% -25% -20% -15% -10% -5% 0% All Group 1 Group 2 Group 3 Group 4Oxygen Benefit (Percent per %) FTP Bag 1

-40% -35% -30% -25% -20% -15% -10% -5% 0% All Group 1 Group 2 Group 3 Group 4Oxygen Benefit (Percent per %) FTP Bag 3 -40% -35% -30% -25% -20% -15% -10% -5% 0% All Group 1 Group 2 Group 3 Group 4Oxygen Benefit (Percent per %) FTP Bag 2



### ###

### -42- 

## 5. STATISTICAL ANALYSIS AND DEVELOPMENT OF EMISSION CORRECTION FACTORS

5.1 Overview

This section presents a statistical analys is of the E-74b THC, CO, and NOx emissions data. The results of the analysis are presented in detail and then summarized in the form of correction factor equations for use at te mperatures below 75°. While subsets of the data were examined in Section 4, the analysis discussed in this sec tion is based on all of the fuels tested in the E74-b program, with RVP values ranging from 7 to 13 psi and oxygen content ranging from E0 to E20. However, not all combinations of temperature, RVP, and oxygen content were tested. The E20 oxygenati on level was tested only for RVP 9 fuels (but at both 50°F and 75°F), while the RVP 7 fuels (at E0 and E10) were tested only at 75°F.

As described below, the statistical analys is has been conducted twice to address the potential impacts of variation in T 50 

### in test fuels 2 and 4 relative to the other test fuels. The primary analysis presented in Section 5.3 is based on the E-74b design variables: temperature, RVP, and oxygen content. This formulation of the analysis will include, in the coefficients estimated for the RVP and oxygen terms, the emission effects (if any) caused by variations in T 50 

### for test fuels 2 and 4. The second analysis, described in Section 5.4, was conducted to test the sensitivity of the primary results by including a T 50 

### term in models that are otherwise similar, except for the statistically confounded terms that must be excluded.

Lastly, the development of the correction factor equations is described and the results are compared with the correction factors incor porated into MOBILE6.2 and with correction factors previously developed by Sierra. *



## 5.2 Methodology

5.2.1 Mathematical Formulation The effects of ambient temperature, RVP, and oxygen content on emissions are represented in MOBILE6.2 in the form of e quations that adjust emission factors at FTP conditions to reflect emission rates at non-FT P conditions. For temperatures above 75°F,

* Heirigs, P.L., and Lyons, J.M, “Review of Current and Future CO Emissions from On-Road Vehicles in Selected Western Areas,” Sierra Research Report No. SR03-01-01, January 28, 2003.

### -43- the MOBILE6.2 correction factor equations ta ke the form of a statistical response surface, including linear terms in temperature, RVP, and oxygen content and a number of their two-way interactions. A simplified form is implemented for temperatures below 75°F.

The statistical analysis conducted here uses the most complete, second-order response surface in the design variables temperatur e, RVP, and oxygen content that can be estimated for the data, including all linear terms, all two-way interactions, and a quadratic term in oxygen content (the only variable tested at three levels). This formulation is very similar to that used in MOBILE6.2 for temperatures above 75°F.

The mathematical form of the general second-order response surface used here is given in Eq. 5-1:

ln E = ln E 0 

### + C T 

### · T + C T,O2 

### · T · OxPct

+ C RVP-L 

### · RVP L 

### + C RVP-H 

### · RVP H 

### + C RVP-H,T 

### · RVP H 

### · T + C RVP,O2 

### · RVP OxPct

+ C 1,O2 

### · OxPct + C 2,O2 

### · OxPct 2 

### (Eq. 5-1)

where: T = T - 75°F RVP L 

### = min(0, RVP – 9 psi) RVP H 

### = max(0, RVP – 9 psi) RVP = RVP – 9 psi OxPct = Oxygen content (as a weight percent, not decimal fraction)

This formulation provides separa te slopes for the effect of RVP below and above 9 psi to accommodate the evidence that RVP effects differ between these regimes. One regime is that of RVP values between 7 and 9 psi in which vehicles must demonstrate compliance with federal and California certification standards. Vehicle performance in this regime is constrained by the certification process. The second regime is that of RVP values above 9 psi, in which vehicle certification does not directly constrain vehicle performance. In this regime, fuels are formulated on a seasonal basis (primarily for winter) with RVP levels selected to achieve satisfactory vehicle startup and driveability.

RVP values below 9 psi are measured by the variable RVP L 

### , which is zero for fuels with RVP above 9 psi. The RVP L 

### slope is included in the statis tical models to provide a test for whether emissions differ between 7 and 9 ps i. The slope is retained in all models without regard to statistical significance to distinguish emissions between the two regimes. The earlier CRC E74-a program demonstrated that there is no statistically significant difference in vehicle certifica tion emissions between 7 and 9 psi, and the exploratory analysis in the preceding section showed that there is no statistically significant difference in in-use vehicle CO emissions in the current program. The a priori hypothesis is that the RVP L 

### slope will fail to be statistically significant.

### -44- RVP values above 9 psi are measured by the variable RVP H 

### , which is zero for fuels with RVP below 9 psi. The RVP H 

### slope is included in the model to measure the extent to which RVP values in excess of 9 psi have an effect on vehicle emissions compared to emissions at the RVP = 9 psi value used fo r certification. Based on prior research, the a priori hypothesis is that higher fuel volatility will, in some cases, have an adverse effect on HC and CO emissions at 75°F, but may have no effect, or possibly a beneficial effect, at colder temperatures. NOx emissions effect s are expected to counter the HC/CO trends.

The response surface is linear with respect to T, RVP L 

### , and RVP H 

### . It includes all twoway interaction terms between the variables that can be tested, including interactions between T and RVP H 

### , RVP and OxPct, and T and OxPct. Because oxygen content was tested at three levels, a non-linear response surface is fit with respect to OxPct, from which the potential for changes in oxygenate response rates over the range from E0 to E20 can be evaluated. The inter action terms T · OxPct and T · RVP H 

### represent the potential for the oxygen and RVP effects to differ between 50°F and 75°F. The term RVP · OxPct represents the potential interaction of RVP and OxPct, such that the observed emissions change differs from what would be expected from the two variables alone.

The functional form of Eq. 5-1 measures te mperature and RVP as departures from the FTP conditions (75°F, RVP = 9 psi, 0% oxygen content), so that the intercept term E 0 

### estimates emissions at FTP conditions. Because the emissions intercept term is vehiclespecific, and is either absorbed (removed from the analysis) or specified as dummy variables, it is of no dire ct interest in the understanding of emissions changes relative to FTP conditions. Therefore, intercept terms are not reported in the results of the analysis.

These key trends described in Section 4 for CO are incorporated, along with corresponding trends for HC and NOx, in th e statistical analysis and the updated correction factor equa tions developed here:

 A widespread oxygenate effect in which CO emissions are reduced with increasing gasoline oxygen content by an amount that varies by FTP phase but is relatively consistent in size across tec hnology groups. This effect may show evidence of diminishing returns for CO, in which the marginal benefit of further oxygenation decreases as oxygen content rises.

 Little or no effect on CO emissions at 75°F for fuel RVP values below 9 psi.

 An effect of increasing CO emissions with gasoline RVP between 9 and 13 psi that is substantially larger at 75°F than at 50°F. The effect varies by FTP phase and by vehicle technology group. However, th e effect is restricted to RVP values in excess of 9 psi, based on the absence of statistically significant evidence for emission effects at 7 psi.

 For cold ambient temperatures (50°F), there is evidence that increasing gasoline RVP to 13 psi causes a reduction in CO emissions during Bag 1. This “cold-

### -45- temperature benefit” is not detected in the other FTP phases or for the other pollutants. This effect is represented in the analysis as an RVP · T interaction that reverses sign and becomes an emissions benefit at temperatures below 75°F.

 In addition to these fuel effects, the adjustment factor analysis estimates coldtemperature emissions offsets by FTP phase for the testing at 50°F.

5.2.2 Conduct of the Analysis

5.5.2.1 Overall Fleet – The analysis was conducted in a standardized sequence for each of the 12 analysis cells formed from the in tersection of pollutant (CO, HC, NOx) and FTP test phase (Composite, Bag 1, Bag 2, Bag 3). To begin the analysis for each cell, the full response surface was estimated using ordi nary least squares regression analysis applied to the data for all vehicles. Its key results (coefficient estimates and p values) are reported under the heading Full Model in the tables found in Section 5.3. As will be seen, the second-order response surface is ove r-specified in general—meaning that it contains more terms than are needed to repres ent the trends in the data. Because many of the terms have correlations of non-negligible size, there is a tendency for the terms in the Full Model to show poor or no statistical signif icance. Thus, there is a need to reduce the model to include only those terms that represent meaningful and statistically significant effects.

The second stage of the analysis involved the use of stepwise regression techniques to choose among the terms in Eq. 5-1 to find those that are statistically significant. Both forward- and backward-selection techniques were used. In forward selection, one starts with a model containing only the intercept and RVP L 

### terms; the terms with strongest statistical significance are then added one by one until no remaining term achieves at least p=0.10. In backward selection, all term s are initially introduced in the model, and those terms not achieving p=0.10 are remove d one by one until all terms remaining achieve at least p=0.10. In this, the RVP L 

### term is required to remain in the model. Because stepwise regression cannot be counted on to always find the “best” choice of terms, the results of the two selection methods were compared and judgment was applied in the instances where the methods disagree d. The results of the final models are reported in the tables under the heading Reduced Model

.

An Outlier Assessment was conducted based on the residua ls from the Reduced Model. In this assessment, the observed value for each emissions test was compared to the 99% confidence limits for the value predicted by the regression model. A “good” data point has 1 chance in 100 of lying outside the prediction confidence limits merely by chance, and in a data set of 180 tests it is likely that a few tests will do so in each instance. The tests flagged as potential outliers by this method were then examined to determine if they should be excluded from the data. Only test s substantially outside the confidence limits and appearing to diverge from the predicte d trends would be excluded. After other adjustments made to the data to include certai n vehicles or categorie s of tests (identified below), no individual tests were excluded on this basis as outliers.

### -46- 5.2.2.2 Technology Groups – A second round of analysis was conducted to identify terms that take on different values in one or mo re of the four vehicle technology groups. Stepwise regression techniques were again used to select among an enlarged pool of model terms, including all of the individual terms shown in Eq. 5-1 plus additional terms that allowed the coefficients to differ in any of the four groups. The form of the Reduced Model, the form and statisti cal significance of terms in the technology-based models selected by stepwise regression, and analys t judgment were combined to select final Technology Models reported in the tables. No statistically significant differences were found for any of the four technology Groups individually, perhaps due to the small sample of vehicles in each group, but it was determined that effects sometimes displayed statistical differences when divided into two groups (G roups 1 and 2 combined, and Groups 3 and 4 combined). However, the an alysis more often finds a technologically uniform response, at least wh en measured on a percentage basis and within the sample size limits of the dataset.

Given the form selected for the final Te chnology Models, the outlier analysis was repeated for individual tests, and a furthe r analysis of residuals was conducted to determine if the emissions respons e to T, RVP, RVP · T, or OxPct varied to a statistically significant extent with respect to any of the following distinctions:

 By the four vehicle technology groups;

 By the three exhaust technology groups;

 By the three evaporative technology groups;

 By PC and LDT groups; or

 By individual vehicle.

The further residual analyses employed the F test to determine if there was sufficient evidence to conclude that one or more of the several (to many) levels in each distinction were different from the rest. Statistically significant differences were investigated, leading either to decisions to adjust the sta tistical models or to exclude divergent data until such differences were resolved. The adjustments are discussed below.

1. The FTP Bag 3 CO emissions of many vehicles are reported as 0.00 gm/mi, as a consequence of the inherently low emissi on levels of new vehicles that employ sophisticated exhaust and evaporative e mission controls. Although the emission readings were reset to a de minimus level of 0.005 to permit inclusion in the log models, the response coefficients estima ted for the Tier 2 Groups in the technology analysis were often weak a nd sometimes counter-intuitive. A decision was made to exclude all data points with FTP Bag 3 CO = 0.00 gm/mi from the Bag 3 CO analysis, reducing the number of total data points to N = 156. Bag 3 CO emissions are so low for vehicles in Groups 3 and 4 that it is doubtful whether temperature or RVP effects would be larg e enough to be meaningful in inventory analysis, if they could be detected with statistical significance in a larger dataset of vehicle testing.

### -47- 2. The analysis of FTP Bag 2 CO emissions demonstrated that Vehicle 7 (2001 Dodge Caravan) had a distinctive response to RVP 7 fuels, as had been noted in the exploratory analysis of the prior section, in which its Bag 2 CO emissions were measured as 0.00 gm/mi on both RVP fu els. Rather than exclude the two Vehicle 7 tests from the dataset, a separate term was introduced to allow a different RVP L 

### response for this vehicle alone.

3. The analysis of FTP Bag 1 THC emissions indicated that the performance of Vehicle 11 (2004 Toyota Camry) was consis tently different from that of other vehicles. Specifically, it had higher THC emissions at 50°F (by 25%, p=0.00) and higher emissions at 50°F on RVP 13 fuel (by 29%, p=0.03) in comparison to other Tier 2 vehicles under comparable conditions. Because the results suggest the possibility of engine or emission controls operating improperly at cold start under low ambient temperature, the data for this vehicle were dropped entirely from the analysis of the FTP Composite and Bag 1. The vehicle’s data were retained for Bags 2 and 3, for which there was no indication of a significant difference compared to other vehicles.

4. FTP Bag 1 NOx emissions were found to vary significantly between PCs and LDTs with respect to the response to RVP (p=0.03) and to the interaction of RVP and temperature (p=0.03). A final tec hnology model was fit to capture this difference in the correction factor equati ons. It shows that PC NOx emissions have no measurable sensitivity to RVP in FTP Bag 1, but that LDT NOx emissions are increased by a statistically significant amount when using high RVP fuel. Although FTP Composite emissions are computed from the bag-specific emissions, the PC/LDT difference for Bag 1 NOx is not detected with statistical confidence in FTP Composite NOx emissions.

Except for the adjustments itemized above, no ot her deletions were made for outliers. In general, the data points identified by the outlier test most often lie at low emission values, where they are flagged as potential outliers because they show large percentage differences from the log-emissions regressi on line. However, even large percentage differences applied to a very small emissions estimate may amount to no more than a few tenths of 1 gm/mi and, therefore, are not of substantive concern.



## 5.3 Statistical Analysis Results (Primary)

The results of the statistical analysis are repor ted in Tables 5-1 through 5-12, in a format that should be easily understood from the preceding discussion of the analysis methodology. The analysis reported in this section is the primary statistical analysis, in which only design effects are included in the model formulation. As explained previously, the presence of a much lower T 50 

### temperature in two of the test fuels causes the analysis to face the problem of statisti cal confounding. The results of a sensitivity analysis are presented in Section 5.4 as an alternative to this primary analysis.

### -48- 5.3.1 FTP Composite CO Emissions The results of the statistical analysis for FTP Composite CO (Table 5-1) are briefly described to ensure understanding of the resu lts shown in Tables 5-1 through 5-12. The coefficient values given in the tables pert ain to the Eq. 5 model of log emissions; the corresponding percentage effect on emissions can be calculated as exp(coefficient)-1.

A first round of analysis examined the data as a whole, without consideration of technology differences. The Full Model section of the table reports the results for the fit of the complete second-order response surface. Of the eight possible terms (excluding the intercept), there is no evidence that the effect of oxygen content on Composite CO emissions varies with temperat ure (the interaction term T · OxPct). Further, there is no evidence that RVP values below 9 psi have an effect on Composite CO (the RVP term) or that the effect of oxygen content varies with respect to RVP (the RVP · OxPct term). All other terms are statistically significant at acceptable confidence levels or better.

The Reduced Model reports the results for the statistically significant effects once the T · OxPct and RVP · OxPct interaction terms are omitted. The RVP term is retained in the Reduced Model, even though it lacks statistical significance, to distinguish emission levels between the two RVP regimes. As shown for the outlier assessment , only three tests lie outside the 99% confid ence intervals for the predictions of the reduced model. The number of such tests is only slightly grea ter than the 1.8 tests that would be expected in a sample of N=180 tests. After inspection of a graphical display of the data, no points were excluded as outliers.

The Technology Model section of the table reports th e results of a second round of analysis to determine whether any of the te rms in Eq. 5-1 vary by vehicle technology group. In the analysis, each term (including terms not found to be statistically significant in the first round of analysis) is tested for in clusion in the model in seven different forms:

 As a uniform coefficient applicable to all vehicles;

 As coefficients that differ in one or more of the four vehicle technology groups; and

 As coefficients that diffe r between two composite groups consisting of Groups 1 and 2 combined (Tier 1/NLEV) and Groups 3 and 4 combined (the two Tier 2 Groups).

The technology model is then built from the term s that are found to fit the data with an acceptable level of statistical significance (p =0.10 or better). Correc tion factor equations for use in MOBILE6.2 are derived from the tech nology models, as will be summarized in Section 5.5.

For FTP Composite CO, the technology analysis finds that the T and RVP effects and the RVP · T interaction differ between the co mposite Groups 1 and 2 and the composite Groups 3 and 4 to a statistically significant degree. Groups 3 and 4 (vehicles certified to Tier 2 exhaust emission standards) have a slightly larger temperature sensitivity (on a

### -49- percentage basis), but they have a substa ntially smaller RVP re sponse and a smaller RVP · T interaction term.

The oxygenate effect is found to be uniform across all technology gr oups and of the same size at both 50°F and 75°F ambient temperatures and at all three RV P levels. The data clearly indicate that the CO emissions bene fit of oxygenated gasoline is subject to diminishing returns as the oxygen content increases beyond E10. The quadratic form (C 1 

### + C 2 

### ) · OxPct is shown to be statistically sign ificant at the p=0.01 level or better. The maximum point (the point of maximum CO benefit) is computed by the formula:

OxPct max 

### = -C 1 

### / (2 · C 2 

### ) (Eq. 5-2)

For the values C 1 

### and C 2 

### estimated here, the maximum bene fit is reached at an oxygen content of 6.9% or E18.8. The emissions benefit of oxygenation is subject to significantly diminished returns as oxygen content is increased beyond E10. At the E10 level oxygenation is estimated to reduce FTP Composite CO emissions by 26%, but increasing oxygenation to E18.8 exte nds the CO reduction to only 30%.

Although the quadratic form changes direction beyond the maximum point, the analysis does not provide a definitive answer on the trend of emissions with oxygen content beyond the maximum point—i.e., whether emissi ons are constant beyond the maximum or turn back up to follow the trend of reduced benefit (increased emissions) that is predicted by the quadratic beyond the maximum point. Further, no information is available in the E74-b data for oxygen content beyond that of E20. What is clear is that oxygenation of gasoline is subject to diminishing returns as the oxygen content is increased and that oxygenation of gasoline beyond the maximum point is not likely to carry appreciable incremental emissions benefit. As a practical matter, the estimated maximum benefit should be held constant at higher oxyg enation levels in applying the results of this analysis.

Because only Fuel 4 was blended with an oxygenate level of E20, the observed nonlinearity in the oxygenate effect is dependent on the emission performance of Fuel 4. As indicated in Section 4, Fuel 4 was blended with a T 50 

### level some 30°F below the range of the five closely controlled fuels, so that th e observed non-linearity of the oxygenate effect may be due, in whole or in part, to the low T 50 

### temperature of Fuel 4.

5.3.2 Summary of Statistical Analysis Results Tables 5-1 through 5-12 summarize the results of the primary statistical analysis. With one exception, the technology models summarize d in the tables are the final models from which the correction factor equations were de veloped. For FTP Bag 1 NOx, the test data show a clear difference in the RVP H 

### and RVP H 

### · T response between passenger cars (PCs) and light-duty trucks (LDTs). An expanded model was fit for the purpose of estimating PC and LDT correction factors, and its coefficients are tabulated in Section 5.4. All terms in the model ach ieve p=0.05 values or better.

### -50- Table 5-1 Model Summary for CO FTP Composite (N=180, 15 Vehicles)
Coefficient Prob>|t|

Full Model Intercept -- -- T (T-75) -0.01857 0.00


### T · OxPct 0.00006 0.93

RVP L (RVP-9) 0.00013 1.00
RVP H (RVP-9) 0.07946 0.00


### RVP H 

### · T 0.00370 0.00


### RVP · OxPct -0.00360 0.60
OxPct -0.09466 0.00
OxPct 

### · OxPct 0.00640 0.09
Reduced Model T (T-75) -0.01879 0.00

RVP L (RVP-9) 0.00001 1.00

RVP H (RVP-9) 0.07271 0.00

RVP 

### · T 0.00373 0.00
OxPct -0.10337 0.00
OxPct 

### · OxPct 0.00746 0.02
Outlier Assessment Tests with p<0.01 a 3
Tests Excluded none Technology Model T Groups 1+2 -0.01315 0.00 Groups 3+4 -0.02519 0.00
RVP L (RVP-9) All -0.00025 0.99
RVP H Groups 1+2 0.10843 0.00 Groups 3+4 0.03396 0.12

RVP 

### · T Groups 1+2 0.00474 0.00 Groups 3+4 0.00276 0.03
OxPct -0.10312 0.00
OxPct



### · OxPct b 0.00743 0.01

a Expected tests with p<0.01 = 1.8
b Asymptote for OxPct = 6.9% or E18.8

### -51- Table 5-2 Model Summary for CO FTP Bag 1 (N=180, 15 Vehicles) Coefficient Prob>|t|

Full Model Intercept -- -- T (T-75) -0.02751 0.00

T



### · OxPct 0.00035 0.57
RVP L (RVP-9) -0.03644 0.31
RVP H (RVP-9) 0.05231 0.01

RVP H 

### · T 0.00315 0.00

RVP 

### · OxPct -0.00717 0.25
OxPct -0.09410 0.00
OxPct



### · OxPct 0.00754 0.03
Reduced Model T (T-75) -0.02623 0.00
RVP L (RVP-9) -0.02974 0.39
RVP H (RVP-9) 0.03591 0.02

RVP



### · T 0.00299 0.00
OxPct -0.11536 0.00
OxPct · OxPct 0.00950 0.00
Outlier Assessment Tests with p<0.01 a 4
Tests Excluded none Technology Model T Groups 1+2 -0.02377 0.00 Groups 3+4 -0.02896 0.00
RVP L (RVP-9) All -0.02967 0.38
RVP H Groups 1+2 0.03599 0.02 Groups 3+4 Same RVP · T Groups 1+2 0.00300 0.00 Groups 3+4 Same
OxPct -0.11523 0.00
OxPct · OxPct b 0.00949 0.00

a Expected tests with p<0.01 = 1.8
b Asymptote for OxPct = 6.3% or E16.9

### -52- Table 5-3 Model Summary for CO FTP Bag 2 (N=180, 15 Vehicles) Coefficient Prob>|t|

Full Model Intercept -- -- T (T-75) 0.01718 0.20
T · OxPct -0.00473 0.07
RVP L (RVP-9) 0.33022 0.03
RVP H (RVP-9) 0.13600 0.11
RVP H · T -0.00486 0.20
RVP · OxPct 0.00041 0.99
OxPct -0.10208 0.35
OxPct · OxPct -0.00514 0.72
Reduced Model T (T-75) -- -- RVP L (RVP-9) 0.03584 0.74
dVeh07 · RVP L 3.32832 0.00
RVP H (RVP-9) 0.16848 0.00
RVP H · T 0.00705 0.00
OxPct -0.08735 0.00
OxPct · OxPct -- -- Outlier Assessment Tests with p<0.01 a 6
Tests Excluded none Technology Model T Groups 1+2 -- -- Groups 3+4 -- --
RVP L (RVP-9) All 0.03584 0.74
dVeh07 · RVP L 3.32832 0.00
RVP H Groups 1+2 0.16848 0.00 Groups 3+4 Same RVP · T Groups 1+2 0.00705 0.00 Groups 3+4 Same
OxPct -0.08735 0.00
OxPct · OxPct n/a

a Expected tests with p<0.01 = 1.8

### -53- Table 5-4 Model Summary for CO FTP Bag 3 (N = 156, excluding Tests with CO Ba g 3 

### = 0.000) Coefficient Prob > |t|

Full Model Intercept -- -- T (T-75) 0.00307 0.66
T · OxPct 0.00022 0.87
RVP L (RVP-9) 0.02292 0.76
RVP H (RVP-9) 0.10408 0.02
RVP H · T 0.00138 0.49
RVP · OxPct -0.01126 0.40
OxPct -0.10838 0.05
OxPct · OxPct 0.00905 0.22
Reduced Model T (T-75) -- -- RVP L (RVP-9) 0.00248 0.97
RVP H (RVP-9) 0.06640 0.01
RVP · T -- -- OxPct -0.13783 0.00
OxPct · OxPct 0.01191 0.06
Outlier Assessment Tests with p<0.01 a 4
Tests Excluded none Technology Model T Groups 1+2 -- -- Groups 3+4 -- --
RVP L (RVP-9) All 0.02253 0.71
RVP H Groups 1+2 0.14635 0.00 Groups 3+4 None
RVP H · T Groups 1+2 0.00527 0.00 Groups 3+4 None
OxPct -0.13279 0.00
OxPct · OxPct b 0.01105 0.06

a Expected tests with p<0.01 = 1.6
b Asymptote for OxPct = 6.0% or E16.2

### -54- Table 5-5 Model Summary for THC FTP Composite (N = 168, excluding Vehicle 11)
Coefficient Prob>|t|

Full Model Intercept -- -- T (T-75) -0.01164 0.00
T · OxPct -0.00058 0.11
RVP L (RVP-9) 0.00022 0.99
RVP H (RVP-9) 0.01679 0.15
RVP H · T 0.00059 0.26
RVP · OxPct -0.00075 0.83
OxPct -0.02045 0.18
OxPct · OxPct 0.00006 0.98
Reduced Model T (T-75) -0.01026 0.00
T · OxPct -0.00071 0.04
RVP L (RVP-9) 0.01840 0.29
RVP H (RVP-9) -- -- RVP H · T -- -- OxPct -0.02281 0.00
OxPct · OxPct -- -- Outlier Assessment Tests with p<0.01 a 3
Tests Excluded none Technology Model T Groups 1+2 -0.00812 0.00 Groups 3+4 -0.01301 0.00
T · OxPct -0.00072 0.03
RVP L (RVP-9) All 0.01850 0.27
RVP H Groups 1+2 -- -- Groups 3+4 -- --
RVP H · T Groups 1+2 -- -- Groups 3+4 -- --
OxPct -0.02279 0.00

a Expected tests with p<0.01 = 1.7

### -55- Table 5-6 Model Summary for THC FTP Bag 1 (N = 168, excluding Vehicle 11) Coefficient Prob>|t|

Full Model Intercept -- -- T (T-75) -0.01760 0.00
T · OxPct -0.00074 0.08
RVP L (RVP-9) -0.00613 0.80
RVP H (RVP-9) 0.01549 0.25
RVP H · T 0.00080 0.19
RVP · OxPct -0.00087 0.83
OxPct -0.02842 0.11
OxPct · OxPct 0.00069 0.76
Reduced Model T (T-75) -0.01579 0.00
T · OxPct -0.00092 0.02
RVP L (RVP-9) 0.00909 0.65
RVP H (RVP-9) -- -- RVP H · T -- -- OxPct -0.02634 0.00
OxPct · OxPct -- -- Outlier Assessment Tests with p<0.01 a 4
Tests Excluded None Technology Model T Groups 1+2 -0.01379 0.00 Groups 3+4 -0.01835 0.00
T · OxPct -0.00092 0.02
RVP L (RVP-9) 0.00919 0.64
RVP H Groups 1+2 -- -- Groups 3+4 -- -- RVP · T Groups 1+2 -- -- Groups 3+4 -- --
OxPct -0.02633 0.00

a Expected tests with p<0.01 = 1.7

### -56- Table 5-7 Model Summary for THC FTP Bag 2 (N=180, 15 Vehicles) Coefficient Prob>|t|

Full Model Intercept -- -- T (T-75) 0.00410 0.23
T · OxPct -0.00079 0.24
RVP L (RVP-9) 0.02665 0.49
RVP H (RVP-9) 0.00926 0.97
RVP H · T -0.00086 0.38
RVP · OxPct 0.00177 0.79
OxPct 0.02271 0.42
OxPct · OxPct -0.00510 0.16
Reduced Model T (T-75) -- -- T · OxPct -- -- RVP L (RVP-9) 0.02654 0.37
RVP H (RVP-9) -- -- RVP H · T -- -- OxPct
OxPct · OxPct
Outlier Assessment Tests with p<0.01 a 1
Tests Excluded None Technology Model T Groups 1+2 -- -- Groups 3+4 -- --
T · OxPct -- -- RVP L (RVP-9) All -0.00258 0.93
RVP H Groups 1+2 0.06932 0.00 Groups 3+4 0.00230 0.02 RVP · T Groups 1+2 -- -- Groups 3+4 -- --
OxPct -- --

a Expected tests with p<0.01 = 1.8

### -57- Table 5-8 Model Summary for THC FTP Bag 3 (N=180, 15 Vehicles) Coefficient Prob>|t|

Full Model Intercept -- -- T (T-75) 0.00613 0.02
T · OxPct -0.00072 0.17
RVP L (RVP-9) 0.00241 0.93
RVP H (RVP-9) 0.02259 0.18
RVP H · T -0.00020 0.79
RVP · OxPct -0.00448 0.38
OxPct -0.00362 0.87
OxPct · OxPct -0.00135 0.63
Reduced Model T (T-75) 0.00387 0.01
T · OxPct -- -- RVP L (RVP-9) -0.00662 0.81
RVP H (RVP-9) 0.01942 0.03
RVP H · T -- -- OxPct -- -- OxPct · OxPct -- -- Outlier Assessment Tests with p<0.01 a 2
Tests Excluded none Technology Model
T Groups 1+2 0.00039 0.01 Groups 3+4 same
RVP L (RVP-9) -0.00662 0.81
RVP H Groups 1+2 0.01942 0.03 Groups 3+4 same RVP · T Groups 1+2 -- -- Groups 3+4 -- --
OxPct -- --

a Expected tests with p<0.01 = 1.8

### -58- Table 5-9 Model Summary for NOx FTP Composite (N=180, 15 Vehicles) Coefficient Prob>|t|

Full Model Intercept -- -- T (T-75) -0.00397 0.16
T · OxPct -0.00069 0.22
RVP L (RVP-9) -0.01120 0.73
RVP H (RVP-9) 0.03777 0.04
RVP H · T -0.00026 0.75
RVP · OxPct -0.00411 0.46
OxPct 0.01520 0.52
OxPct · OxPct 0.00056 0.85
Reduced Model T (T-75) -0.00644 0.00
T · OxPct -- -- RVP L (RVP-9) -0.01831 0.53
RVP H (RVP-9) 0.03134 0.00
RVP H · T -- -- OxPct 0.02362 0.00
OxPct · OxPct -- -- Outlier Assessment Tests with p<0.01 a 3
Tests Excluded none Technology Model T Groups 1+2 -0.00691 0.00 Groups 3+4 -0.00594 0.01
RVP L (RVP-9) All -0.01834 0.53
RVP H Groups 1+2 0.03135 0.00 Groups 3+4 same
RVP H · T Groups 1+2 -- -- Groups 3+4 -- --
OxPct 0.02361 0.00

a Expected tests with p<0.01 = 1.8

### -59- Table 5-10 Model Summary for NOx FTP Bag 1 (N=180, 15 Vehicles) Coefficient Prob>|t|

Full Model Intercept -- -- T (T-75) -0.00696 0.00
T · OxPct -0.00060 0.21
RVP L (RVP-9) -0.01051 0.70
RVP H (RVP-9) 0.00833 0.58
RVP H · T -0.00061 0.37
RVP · OxPct 0.00216 0.64
OxPct -0.00651 0.74
OxPct · OxPct 0.00235 0.36
Reduced Model T (T-75) -0.00974 0.00
T · OxPct -- -- RVP L (RVP-9) -0.02198 0.38
RVP H (RVP-9) 0.01855 0.03
RVP H · T -- -- OxPct 0.01670 0.00
OxPct · OxPct -- -- Outlier Assessment Tests with p<0.01 a 2
Tests Excluded none Technology Model T Groups 1+2 -0.01046 0.00 Groups 3+4 -0.00896 0.00
RVP L (RVP-9) All -0.02204 0.38
RVP H Groups 1+2 0.01857 0.03 Groups 3+4 Same
RVP H· · T Groups 1+2 -- -- Groups 3+4 -- --
OxPct 0.01669 0.00

a Expected tests with p<0.01 = 1.8

### -60- Table 5-11 Model Summary for NOx FTP Bag 2 (N=180, 15 Vehicles) Coefficient Prob>|t|

Full Model Intercept -- -- T (T-75) -0.00514 0.52
T · OxPct 0.00031 0.84
RVP L (RVP-9) -0.12002 0.18
RVP H (RVP-9) 0.16090 0.00
RVP H · T 0.00191 0.40
RVP · OxPct -0.03218 0.04
OxPct 0.04019 0.54
OxPct · OxPct 0.00191 0.82
Reduced Model T (T-75) -- -- T · OxPct -- -- RVP L (RVP-9) -0.08755 0.26
RVP H (RVP-9) 0.14026 0.00
RVP H · OxPct -0.03448 0.01
OxPct 0.05243 0.01
OxPct · OxPct -- -- Outlier Assessment Tests with p<0.01 a 2
Tests Excluded none Technology Model T Groups 1+2 -- -- Groups 3+4 -- --
RVP L (RVP-9) All -0.07059 0.37
RVP H Groups 1+2 0.06209 0.03 Groups 3+4 Same
RVP H · T Groups 1+2 -- -- Groups 3+4 -- --
OxPct 0.03110 0.01

a Expected tests with p<0.01 = 1.8

### -61- Table 5-12 Model Summary for NOx FTP Bag 3 (N=180, 15 Vehicles) Coefficient Prob>|t|

Full Model Intercept -- -- T (T-75) 0.00669 0.22
T · OxPct -0.00202 0.06
RVP L (RVP-9) -0.01100 0.86
RVP H (RVP-9) 0.05348 0.12
RVP H · T -0.00011 0.94
RVP · OxPct -0.00726 0.50
OxPct 0.05997 0.18
OxPct · OxPct -0.00605 0.30
Reduced Model T (T-75) -- -- T · OxPct -- -- RVP L (RVP-9) -0.03790 0.47
RVP H (RVP-9) 0.04520 0.02
RVP H · T -- -- OxPct 0.03620 0.00
OxPct · OxPct -- -- Outlier Assessment Tests with p<0.01 a 4
Tests Excluded none Technology Model T Groups 1+2 -- -- Groups 3+4 -- --
RVP L (RVP-9) All -0.03790 0.47
RVP H Groups 1+2 0.04520 0.02 Groups 3+4 same
RVP H · T Groups 1+2 -- -- Groups 3+4 -- --
OxPct 0.03620 0.00

a Expected tests with p<0.01 = 1.5

### -62- 

## 5.4 Alternative Statistical Analysis

To assess the uncertainty introduced by the confounding of T 50 

### variations with the design effects of RVP and oxygenation, an alterna tive statistical analysis was conducted in which the terms RVP·OxPct and OxPct 2 

### (i.e., the terms that are confounded with the variation in T50) were droppe d from consideration and a T 50 

### term was introduced. This change in formulation of the statistical model shifts part of the explanation of emission changes away from RVP and OxPct to the T 50 

### term.

The mathematical form used in the alternative statistical analysis is given in Eq. 5-3:

ln E = ln E 0 

### + C T 

### · T + C T,O2 

### · T · OxPct

+ C RVP-L 

### · RVP L 

### + C RVP-H 

### · RVP H 

### + C RVP-H,T 

### · RVP H 

### · T + C RVP,O2 

### · RVP · OxPct

+ C 1,O2 

### · OxPct + C 2,O2 

### · OxPct 2 

### (Eq. 5-3)

where: T = T - 75°F RVP L 

### = min(0, RVP – 9 psi) RVP H 

### = max(0, RVP – 9 psi) RVP = RVP – 9 psi OxPct = Oxygen content (as a weight percent, not decimal fraction) dT 50 

### = T 50 

### - 190°F

The alternative statistical analysis was condu cted in a manner similar to that described above, but without repeating the analysis to se lect statistically significant terms in each case, so that the alternative models are comparable to the primary models except for the changes introduced by the dT 50 

### term. As with the primary analysis, a Full Model was initially estimated using th e alternative formulatio n given above. Then, a Reduced Model was estimated by including a dT 50 

### term with the subset of terms in Eq. 5-3 that were included in the models of the primary analysis. The dT 50 

### term is retained in the Reduced Model, even though it is not statistically significant at accepted levels, to show the effect on the coefficients estimated for other terms and to demonstrate the weakness of the dT 50 

### term itself. A Technology Model was estimated in a similar manner, retaining the technology distinctions and terms used in the primary analysis.

Tables 5-13 through 5-24 compile the statistical results of the alternative analysis in comparison to the primary analysis. Inclusion of the dT 50 

### term has the effect of reducing the coefficient estimated for the RVP H 

### effect, while leaving the coefficients of the temperature effect and the RVP · T interaction largely unchanged. The oxygenation effect is now represented by a linear slope for the emissions change between E0 and E20, while the deviation of emissions at E20 from the linear trend is included in the dT 50 

### term. The statistical weakness of the dT 50 

### term suggests that the design effects of RVP and temperature are preferred representations for emission changes, even if their coefficient values are influenced by T 50 

### changes.

### -63- Table 5-13 Alternative Model for CO FTP Composite (N=180, 15 Vehicles) Base Models Including T50 Effect

Coefficient Prob>|t| Coefficient Prob>|t|

Full Model Intercept -- -- -- -- T (T-75) -0.01857 0.00 -0.01889 0.00

T · OxPct 0.00006 0.98 0.00006 0.93

RVP L (RVP-9) 0.00013 -0.00659 0.88

RVP H (RVP-9) 0.07946 0.00 0.05543 0.01

RVP H · T 0.00370 0.00 0.00378 0.00

RVP · OxPct -0.00360 0.92 n/a n/a

OxPct -0.09466 0.00 -0.07007 0.00

OxPct · OxPct 0.00640 0.08 n/a n/a

dT 50 (T 50 –190F) n/a n/a -0.00348 0.35

Reduced Model T (T-75) -0.01879 0.00 -0.01909 0.00

RVP L (RVP-9) 0.00001 1.00 -0.00752 0.85

RVP H (RVP-9) 0.07271 0.00 0.05565 0.01

RVP H · T 0.00373 0.00 0.00380 0.00

OxPct -0.10337 0.00 -0.06965 0.00

OxPct · OxPct 0.00746 0.02 n/a n/a

dT 50 (T 50 –190F) -0.01879 0.00 -0.00352 0.33 Technology Model T Groups 1+2 -0.01315 0.00 -0.01344 0.00 Groups 3+4 -0.02519 0.00 -0.02550 0.00

RVP L (RVP-9) All -0.00025 0.99 -0.00749 0.84

RVP H Groups 1+2 0.10843 0.00 0.09161 0.00 Groups 3+4 0.03396 0.12 0.01725 0.48 RVP · T Groups 1+2 0.00474 0.00 0.00480 0.00 Groups 3+4 0.00276 0.03 0.00284 0.03

OxPct -0.10312 0.00 -0.06918 0.00

dT 50 (T 50 –190F) 0.00743 0.01 -0.00343 0.32

### -64- Table 5-14 Alternative Model for CO FTP Bag 1 (N=180, 15 Vehicles) Base Models Including T50 Effect

Coefficient Prob>|t| Coefficient Prob>|t|

Full Model Intercept -- -- -- -- T (T-75) -0.02751 0.00 -0.02795 0.00

T · OxPct 0.00035 0.57 0.00036 0.58

RVP L (RVP-9) -0.03644 0.31 -0.04108 0.29

RVP H (RVP-9) 0.05231 0.01 0.01944 0.31

RVP H · T 0.00315 0.00 0.00325 0.00

RVP · OxPct -0.00717 0.25 n/a n/a

OxPct -0.09410 0.00 -0.06403 0.00

OxPct · OxPct 0.00754 0.03 n/a n/a

dT 50 (T 50 –190F) -- -- -0.00348 0.30

Reduced Model T (T-75) -0.02623 0.00 -0.02665 0.00

RVP L (RVP-9) -0.02974 0.39 -0.03508 0.34

RVP H (RVP-9) 0.03591 0.02 0.01803 0.34

RVP H · T 0.00299 0.00 0.00309 0.00

OxPct -0.11536 0.00 -0.06670 0.00

OxPct · OxPct 0.00950 0.00 n/a n/a

dT 50 (T 50 –190F) -0.02623 0.00 -0.00324 0.33 Technology Model T Groups 1+2 -0.02377 0.00 -0.02665 0.00 Groups 3+4 -0.02896 0.00 Same

RVP L (RVP-9) All -0.02967 0.38 -0.03508 0.34

RVP H Groups 1+2 0.03599 0.02 0.01803 0.34 Groups 3+4 Same Same

RVP H · T Groups 1+2 0.00300 0.00 0.00309 0.00 Groups 3+4 Same Same

OxPct -0.11523 0.00 -0.06670 0.00

dT 50 (T 50 –190F) n/a n/a -0.00324 0.33

### -65- Table 5-15 Alternative Model for CO FTP Bag 2 (N=180, 15 Vehicles) Base Models Including T50 Effect
Coefficient Prob>|t| Coefficient Prob>|t|

Full Model Intercept -- -- -- -- T (T-75) 0.01718 0.20 0.01736 0.19

T · OxPct -0.00473 0.07 -0.00474 0.07

RVP L (RVP-9) 0.33022 0.03 0.33987 0.03

RVP H (RVP-9) 0.13600 0.11 0.15060 0.06

RVP H · T -0.00486 0.20 0.00482 0.21

RVP · OxPct 0.00041 0.99 n/a n/a

OxPct -0.10208 0.35 -0.11998 0.10

OxPct · OxPct -0.00514 0.72 n/a n/a

dT 50 (T 50 –190F) -- -- 0.00366 0.79

Reduced Model T (T-75) -- -- -- -- RVP L (RVP-9) 0.03584 0.74 0.03779 0.75

dVeh07 · RVP L 3.32832 0.00 3.32832 0.00

RVP H (RVP-9) 0.16848 0.00 0.17009 0.00

RVP H · T 0.00705 0.00 0.00705 0.00

OxPct -0.08735 0.00 -0.08487 0.14

OxPct · OxPct -- -- n/a n/a

dT 50 (T 50 –190F) -- -- 0.00054 0.96 Technology Model T Groups 1+2 -- -- -- -- Groups 3+4 -- -- -- --

RVP L (RVP-9) All 0.03584 0.74 0.03779 0.75

dVeh07 · RVP L 3.32832 0.00 3.32832 0.00

RVP H Groups 1+2 0.16848 0.00 0.17009 0.04 Groups 3+4 Same same

RVP H · T Groups 1+2 0.00705 0.00 0.00705 0.00 Groups 3+4 Same same

OxPct -0.08735 0.00 -0.08487 0.14

dT 50 (T 50 –190F) n/a n/a 0.00054 0.96

### -66- Table 5-16 Alternative Model for CO FTP Bag 3 (N = 156, excluding Tests with CO Ba g 3 

### = 0.000) Base Models Including T50 Effect

Coefficient Prob>|t| Coefficient Prob>|t|

Full Model Intercept -- -- -- -- T (T-75) 0.00307 0.66 0.00252 0.72

T · OxPct 0.00022 0.87 0.00024 0.86

RVP L (RVP-9) 0.02292 0.76 0.02144 0.79

RVP H (RVP-9) 0.10408 0.02 0.06034 0.14

RVP H · T 0.00138 0.49 0.00156 0.44

RVP · OxPct -0.01126 0.40 n/a n/a

OxPct -0.10838 0.05 -0.07098 0.06

OxPct · OxPct 0.00905 0.22 n/a n/a

dT 50 (T 50 –190F) n/a n/a -0.00358 0.61

Reduced Model T (T-75) -- -- -- -- RVP L (RVP-9) 0.00248 0.97 0.00328 0.96

RVP H (RVP-9) 0.06640 0.01 0.07101 0.05

RVP H · T -- -- 0.00230 0.12

OxPct -0.13783 0.00 -0.07256 0.04

OxPct · OxPct 0.01191 0.06 n/a n/a

dT 50 (T 50 –190F) n/a n/a -0.00319 0.65 Technology Model T Groups 1+2 -- -- -- -- Groups 3+4 -- -- -- --

RVP L (RVP-9) 0.02253 0.71 0.00623 0.93

RVP H Groups 1+2 0.14635 0.00 0.12626 0.00 Groups 3+4 None None

RVP H · T Groups 1+2 0.00527 0.00 0.00526 0.00 Groups 3+4 None None

OxPct -0.13279 0.00 -0.07535 0.01

dT 50 (T 50 –190F) n/a n/a -0.00383 0.52

### -67- Table 5-17 Alternative Model for HC FTP Composite (N = 168, excluding Vehicle 11) Base Models Including T50 Effect
Coefficient Prob>|t| Coefficient Prob>|t|

Full Model Intercept -- -- -- -- T (T-75) -0.01164 0.00 -0.01166 0.00

T · OxPct -0.00058 0.11 -0.00058 0.11

RVP L (RVP-9) 0.00022 0.99 0.00099 0.96

RVP H (RVP-9) 0.01679 0.15 0.01548 0.15

RVP H · T 0.00059 0.26 0.00059 0.26

RVP · OxPct -0.00075 0.83 n/a n/a

OxPct -0.02045 0.18 -0.01994 0.05

OxPct · OxPct 0.00006 0.98 n/a n/a

dT 50 (T 50 –190F) n/a n/a 0.00013 0.95

Reduced Model T (T-75) -0.01026 0.00 -0.01034 0.00

T · OxPct -0.00071 0.04 -0.00069 0.05

RVP L (RVP-9) 0.01840 0.29 0.01069 0.60

RVP H (RVP-9) -- -- -- -- RVP H · T -- -- -- -- OxPct -0.02281 0.00 -0.02672 0.00

OxPct · OxPct -- -- n/a n/a

dT 50 (T 50 –190F) n/a n/a -0.00101 0.48 Technology Model T Groups 1+2 -0.00812 0.00 -0.00820 0.00 Groups 3+4 -0.01301 0.00 -0.01308 0.00

T · OxPct -0.00072 0.03 -0.00069 0.04

RVP L (RVP-9) All 0.01850 0.27 0.01100 0.58

RVP H Groups 1+2 -- -- -- -- Groups 3+4 -- -- -- --

RVP H · T Groups 1+2 -- -- -- -- Groups 3+4 -- -- -- --

OxPct -0.02279 0.00 -0.02660 0.00

dT 50 (T 50 –190F) n/a n/a -0.00098 0.48

### -68- Table 5-18 Alternative Model for HC FTP Bag 1 (N = 140, excluding Vehicle 11) Base Models Including T50 Effect
Coefficient Prob>|t| Coefficient Prob>|t|

Full Model Intercept -- -- -- -- T (T-75) -0.01760 0.00 -0.01765 0.00
T · OxPct -0.00074 0.08 -0.00073 0.08
RVP L (RVP-9) -0.00613 0.80 -0.00631 0.80
RVP H (RVP-9) 0.01549 0.25 0.01214 0.33
RVP H · T 0.00080 0.19 0.00081 0.18
RVP · OxPct -0.00087 0.83 n/a n/a
OxPct -0.02842 0.11 -0.02559 0.03
OxPct · OxPct 0.00069 0.76 n/a n/a
dT 50 (T 50 –190F) n/a n/a -0.00027 0.90
Reduced Model T (T-75) -0.01579 0.00 -0.01583 0.00
T · OxPct -0.00092 0.02 -0.00090 0.02
RVP L (RVP-9) 0.00909 0.65 0.00486 0.84
RVP H (RVP-9) -- -- -- -- RVP H · T -- -- -- -- OxPct -0.02634 0.00 -0.02848 0.00
OxPct · OxPct -- -- n/a n/a
dT 50 (T 50 –190F) n/a n/a -0.00055 0.74 Technology Model T Groups 1+2 -0.01379 0.00 -0.01383 0.00 Groups 3+4 -0.01835 0.00 -0.01838 0.00
T · OxPct -0.00092 0.02 -0.00091 0.02
RVP L (RVP-9) All 0.00919 0.64 0.00515 0.83
RVP H Groups 1+2 -- -- -- -- Groups 3+4 -- -- -- --
RVP H · T Groups 1+2 -- -- -- -- Groups 3+4 -- -- -- --
OxPct -0.02633 0.00 -0.02837 0.00
dT 50 (T 50 –190F) n/a n/a -0.00053 0.75

### -69- Table 5-19 Alternative Model for HC FTP Bag 2 (N = 180, 15 Vehicles) Base Models Including T50 Effect
Coefficient Prob>|t| Coefficient Prob>|t|

Full Model Intercept -- -- -- -- T (T-75) 0.00410 0.23 0.00433 0.20
T · OxPct -0.00079 0.24 -0.00079 0.24
RVP L (RVP-9) 0.02665 0.49 0.03335 0.41
RVP H (RVP-9) 0.00926 0.97 0.01659 0.41
RVP H · T -0.00086 0.38 -0.00091 0.35
RVP · OxPct 0.00177 0.79 n/a n/a
OxPct 0.02271 0.42 0.00368 0.84
OxPct · OxPct -0.00510 0.16 n/a n/a
dT 50 (T 50 –190F) n/a n/a 0.00304 0.39
Reduced Model T (T-75) -- -- -- -- T · OxPct -- -- -- -- RVP L (RVP-9) 0.02654 0.37 0.01669 0.6386
RVP H (RVP-9) -- -- -- -- RVP H · T -- -- -- -- OxPct -0.01021 0.44
OxPct · OxPct n/a n/a
dT 50 (T 50 –190F) n/a n/a -0.00115 0.67 Technology Model T Groups 1+2 -- -- -- -- Groups 3+4 -- -- -- --
T · OxPct -- -- -- -- RVP L (RVP-9) All -0.00258 0.93 0.01063 0.76
RVP H Groups 1+2 0.06932 0.00 0.04831 0.01 Groups 3+4 0.00230 0.02 0.00237 0.90
RVP H · T Groups 1+2 -- -- -- -- Groups 3+4 -- -- -- --
OxPct -- -- 0.00957 0.58
dT 50 (T 50 –190F) n/a n/a 0.00262 0.44

### -70- Table 5-20 Alternative Model for HC FTP Bag 3 (N = 180, 15 Vehicles) Base Models Including T50 Effect

Coefficient Prob>|t| Coefficient Prob>|t|

Full Model Intercept -- -- -- -- T (T-75) 0.00613 0.02 0.00608 0.02

T · OxPct -0.00072 0.17 -0.00072 0.17

RVP L (RVP-9) 0.00241 0.93 0.00987 0.75

RVP H (RVP-9) 0.02259 0.18 0.01966 0.20

RVP H · T -0.00020 0.79 -0.00019 0.80

RVP · OxPct -0.00448 0.38 n/a n/a

OxPct -0.00362 0.87 -0.00665 0.61

OxPct · OxPct -0.00135 0.63 n/a n/a

dT 50 (T 50 –190F) n/a n/a 0.00191 0.48

Reduced Model T (T-75) 0.00387 0.01 0.00370 0.01

T · OxPct -- -- -- -- RVP L (RVP-9) -0.00662 0.81 0.00015 1.00

RVP H (RVP-9) 0.01942 0.03 0.02146 0.02

RVP H · T -- -- -- -- OxPct -- -- -- -- OxPct · OxPct -- -- n/a n/a

dT 50 (T 50 –190F) n/a n/a 0.00164 0.16 Technology Model

T Groups 1+2 0.00039 0.01 0.00370 0.01 Groups 3+4 same -- --

RVP L (RVP-9) All -0.00662 0.81 -0.00015 1.00

RVP H Groups 1+2 0.01942 0.03 0.02146 0.02 Groups 3+4 same -- --

RVP H · T Groups 1+2 -- -- -- -- Groups 3+4 -- -- -- --

OxPct -- -- -- -- dT 50 (T 50 –190F) n/a n/a 0.00164 0.16

### -71- Table 5-21 Alternative Model for NOx FTP Composite (N=180, 15 Vehicles) Base Models Including T50 Effect

Coefficient Prob>|t| Coefficient Prob>|t|

Full Model Intercept -- -- -- -- T (T-75) -0.00397 0.16 -0.00410 0.16

T · OxPct -0.00069 0.22 -0.00068 0.23

RVP L (RVP-9) -0.01120 0.73 -0.00753 0.83

RVP H (RVP-9) 0.03777 0.04 0.02988 0.08

RVP H · T -0.00026 0.75 -0.00023 0.78

RVP · OxPct -0.00411 0.46 n/a n/a

OxPct 0.01520 0.52 0.01887 0.23

OxPct · OxPct 0.00056 0.85 n/a n/a

dT 50 (T 50 –190F) n/a n/a 0.00052 0.86

Reduced Model T (T-75) -0.00644 0.00 -0.00645 0.00

RVP L (RVP-9) -- -- -0.01809 0.56

RVP H (RVP-9) -0.01831 0.53 0.03153 0.02

RVP H · T 0.03134 0.00 -- -- OxPct -- -- 0.002391 0.11

OxPct · OxPct 0.02362 0.00 n/a n/a

dedT 50 (T 50 –190F) n/a n/a 0.000063 0.98 Technology Model T Groups 1+2 -0.00691 0.00 -0.00691 0.00 Groups 3+4 -0.00594 0.01 -0.00594 0.01

RVP L (RVP-9) All -0.01834 0.53 -0.01815 0.56

RVP H Groups 1+2 0.03135 0.00 0.03152 0.02 Groups 3+4 same same

RVP H · T Groups 1+2 -- -- -- -- Groups 3+4 -- -- -- --

OxPct 0.02361 0.00 0.02388 0.11

dT 50 (T 50 –190F) n/a n/a 0.00006 0.98

### -72- Table 5-22 Alternative Model for NOx FTP Bag 1 (N=180, 15 Vehicles) Base Models Including T50 Effect

Coefficient Prob>|t| Coefficient Prob>|t|

Full Model Intercept -- -- -- -- T (T-75) -0.00696 0.00 -0.00700 0.00

T · OxPct -0.00060 0.21 -0.00060 0.21

RVP L (RVP-9) -0.01051 0.70 -0.01704 0.55

RVP H (RVP-9) 0.00833 0.58 0.00479 0.73

RVP H · T -0.00061 0.37 -0.00060 0.38

RVP · OxPct 0.00216 0.64 n/a n/a

OxPct -0.00651 0.74 0.00106 0.93

OxPct · OxPct 0.00235 0.36 n/a n/a

dT 50 (T 50 –190F) -- -- -0.00207 0.40

Reduced Model T (T-75) -0.00974 0.00 -0.00970 0.00

RVP L (RVP-9) -- -- -0.03050 0.25

RVP H (RVP-9) -0.02198 0.38 0.01127 0.32

RVP H · T 0.01855 0.03 -- -- OxPct -- -- 0.00550 0.66

OxPct · OxPct 0.01670 0.00 n/a n/a

dT 50 (T 50 –190F) n/a n/a -0.00243 0.32 Technology Model T Groups 1+2 -0.01046 0.00 -0.01042 0.00 Groups 3+4 -0.00896 0.00 -0.00894 0.00

RVP L (RVP-9) All -0.02204 0.38 -0.03058 0.25

RVP H Groups 1+2 0.01857 0.03 0.01126 0.32 Groups 3+4 Same same

RVP H · T Groups 1+2 -- -- -- -- Groups 3+4 -- -- -- --

OxPct 0.01669 0.00 0.00544 0.66

dT 50 (T 50 –190F) n/a n/a -0.00244 0.32

### -73- Table 5-23 Alternative Model for NOx FTP Bag 2 (N=150, 15 Vehicles) Base Models Including T50 Effect

Coefficient Prob>|t| Coefficient Prob>|t|

Full Model Intercept -- -- -- -- T (T-75) -0.00514 0.52 -0.00594 0.46

T · OxPct 0.00031 0.84 0.00032 0.84

RVP L (RVP-9) -0.12002 0.18 -0.08635 0.37

RVP H (RVP-9) 0.16090 0.00 0.10606 0.03

RVP H · T 0.00191 0.40 0.00211 0.36

RVP · OxPct -0.03218 0.04 n/a n/a

OxPct 0.04019 0.54 0.06005 0.17

OxPct · OxPct 0.00191 0.82 n/a n/a

dT 50 (T 50 –190F) n/a n/a 0.00587 0.48

Reduced Model T (T-75) -- -- -- -- RVP L (RVP-9) -- -- -0.04970 0.55

RVP H (RVP-9) -0.08755 0.26 -- -- RVP H · T 0.14026 0.00 0.07927 0.04

OxPct -0.03448 0.01 0.05762 0.17

OxPct · OxPct 0.05243 0.01 n/a n/a

dT 50 (T 50 –190F) n/a n/a 0.00575 0.48 Technology Model T Groups 1+2 -- -- -- -- Groups 3+4 -- -- -- --

RVP L (RVP-9) All -0.07059 0.37 -0.04970 0.55

RVP H Groups 1+2 0.06209 0.03 0.07927 0.04 Groups 3+4 Same same

RVP H · T Groups 1+2 -- -- -- -- Groups 3+4 -- -- -- --

OxPct 0.03110 0.01 0.05762 0.17

dT 50 (T 50 –190F) n/a n/a 0.00575 0.48

### -74- Table 5-24 Alternative Model for NOx FTP Bag 3 (N=150, 15 Vehicles) Base Models Including T50 Effect

Coefficient Prob>|t| Coefficient Prob>|t|

Full Model Intercept -- -- -- -- T (T-75) 0.00669 0.22 0.00675 0.21

T · OxPct -0.00202 0.06 -0.00202 0.06

RVP L (RVP-9) -0.01100 0.86 0.00761 0.91

RVP H (RVP-9) 0.05348 0.12 0.05987 0.06

RVP H · T -0.00011 0.94 -0.00012 0.94

RVP · OxPct -0.00726 0.50 n/a n/a

OxPct 0.05997 0.18 0.04104 0.16

OxPct · OxPct -0.00605 0.30 n/a n/a

dT 50 (T 50 –190F) n/a n/a 0.00567 0.31

Reduced Model T (T-75) -- -- -- -- RVP L (RVP-9) -- -- -0.02230 0.69

RVP H (RVP-9) -0.03790 0.47 -- -- RVP H · T 0.04520 0.02 0.05803 0.02

OxPct -- -- 0.05600 0.05

OxPct · OxPct 0.03620 0.00 n/a n/a

dT 50 (T 50 –190F) n/a n/a 0.00429 0.44 Technology Model T Groups 1+2 -- -- -- -- Groups 3+4 -- -- -- --

RVP L (RVP-9) All -0.03790 0.47 -0.02230 0.69

RVP H Groups 1+2 0.04520 0.02 0.05803 0.02 Groups 3+4 same same

RVP H · T Groups 1+2 -- -- -- -- Groups 3+4 -- -- -- --

OxPct 0.03620 0.00 0.05600 0.05

dT 50 (T 50 –190F) n/a n/a 0.00429 0.44

### -75- 

## 5.5 Summary of Correction Factors Based on Primary Analysis

This subsection summarizes the coefficient va lues for the correction factor equations developed from the primary analysis. In a ddition, the combined effects of temperature, RVP, and oxygenate effects are separated into their individual contri butions. Tables 5-25 and 5-26 summarize the correction f actor results for CO emissions.

Table 5-25 Correction Factor Coefficients for FTP CO Emissions Composite Bag 1 Bag 2 Bag 3 T Groups 1+2 -0.01315 -0.02327 -- -- Groups 3+4 -0.02519 -0.02846 -- --
RVP H Groups 1+2 0.10843 0.03599 0.16848 0.14635 Groups 3+4 0.03396 none RVP H · T Groups 1+2 0.00474 0.00300 0.00705 0.00527 Groups 3+4 0.00276 none OxPct -0.10312 -0.11523 -0.08735 -0.13279
OxPct · OxPct 0.00743 0.00949 -- 0.01105



### Table 5-26 Estimated Effects of Design Va riables on FTP CO Emissions

(Compared to Design Variable Conditions Stated, Percent)
Design Variable Conditions Composite Bag 1 Bag 2 Bag 3

T = 50°F Groups 1+2 T 75F->50F, RVP=9, E0 39% 81% -- -- Groups 3+4 88% 106% -- -- RVP = 13 psi at 75°F Groups 1+2 RVP 9->13, T=75°F, E0 54% 15% 96% 80% Groups 3+4 15% none RVP = 13 psi at 50°F Groups 1+2 RVP 9->13, T=50°F, E0 - 4% -14% -3% 6% Groups 3+4 -13% none Oxygenation at 75°F and 50°F

E10 E0->E10-E20, RVP = Any,

T = Any -24% -26% -28% -29%
E15 -29% -30% -38% -33%

E20 -30% -30% -48% -33%

### -76- For CO, the effect of non-FTP conditions is la rgely driven by low ambient temperature. At 50°F, CO has increased substantially due to temperature alone (at constant RVP). Increasing gasoline RVP to 13 psi offsets a sm all part of the cold-t emperature emissions increase in Bag 1 and has a small benefit in Bag 2 and a small adverse effect in Bag 3. The Bag 1 RVP effect switches from adverse to beneficial at temperatures below 63°F. At 75°F and higher, increased RVP has a c onsistently adverse effect on CO. Fuel oxygenation at the E10 level decreases CO emissions by 24–29 percent in all Bags and independently of temperature and RVP, but during vehicle start (Bags 1 and 3) little additional benefit is seen from ox ygen content in excess of E10.

To illustrate these trends, Figures 5-1 through 5-6 show estimated CO emissions as a function of temperature and RVP. Emissions for RVP 7 psi fuels are the same as shown for 9 psi because no statistically significant emissions change could be detected for RVP between 7 and 9 psi. Only Group 1 (Tier 1) and Group 4 (Tier 2 Enhanced) vehicles are shown because the trends do not differ for the other groups. As the graphs make clear, the primary effect on Bag 1 CO emissions is cold ambient temperatures, with a relative minor beneficial effect for high RVP gasoline at temperatures below about 55°F. RVP has a much larger and consistently adverse effect in Bags 2 and 3.

Figure 5-1 Group 1, Bag 1 CO Trends

### -77- Figure 5-2 Group 1, Bag 2 CO Trends

Figure 5-3 Group 1, Bag 3 CO Trends

### -78- Figure 5-4 Group 4, Bag 1 CO Trends

Figure 5-5 Group 4, Bag 2 CO Trends

### -79- Figure 5-6 Group 4, Bag 3 CO Trends

Tables 5-27 and 5-28 summarize the correction factor results for THC emissions. As for CO, cold ambient temperatures significantly increase Bag 1 THC emissions. Unlike CO, however, no RVP effect can be detected for Bag 1 THC. For Bags 2 and 3, the RVP effect is found to be the same at both 50°F and 75°F. For Bag 2, gasoline RVP of 13 psi has a substantial effect on THC emissions for Group 1 and 2 vehicles, but only a negligibly small effect is seen for Groups 3 and 4 vehicles. A small but adverse Bag 3 effect is seen for all vehicles. Fuel oxygenation has a small beneficial effect for

Table 5-27 Correction Factor Coefficients for FTP THC Emissions Composite Bag 1 Bag 2 Bag 3 T Groups 1+2 -0.00812 -0.01379 -- 0.00039 Groups 3+4 -0.01301 -0.01835 -- T · OxPct -0.00072 -0.00092 -- --
RVP H Groups 1+2 -- -- 0.06932 0.01942 Groups 3+4 -- -- 0.00230
RVP H · T Groups 1+2 -- -- -- -- Groups 3+4 -- -- -- -- OxPct -0.02279 -0.02633 -- -- OxPct · OxPct -- -- -- --

### -80- Table 5-28 Estimated Effects of Design Va riables on FTP THC Emissions (Compared to Design Variable Conditions Stated, Percent) Design Variable Conditions Composite Bag 1 Bag 2 Bag 3

T = 50°F Groups 1+2 T 75F->50F, RVP=9, E0 23% 41% -- negligible Groups 3+4 38% 58% -- RVP = 13 psi at 75°F Groups 1+2 RVP 9->13, T=75°F, E0 -- -- 32% 8% Groups 3+4 1% RVP = 13 psi at 50°F Groups 1+2 RVP 9->13, T=50°F, E0 -- -- 32% 8% Groups 3+4 1% Oxygenation at 75°F

E10 E0->E10-E20, RVP = Any,

T = 75°F -8% - 9% -- --
E15 -12% -14% -- -- E20 -16% -18% -- --

Oxygenation at 50°F E0->E10-E20, RVP = Any,

T = 50°F negligible negligible -- --



### Composite Bag 1 THC emissions only and only at an ambient temperature of 75°F. The oxygenation benefit decreases with temper ature and is negligible at an ambient temperature of 50°F.

Tables 5-29 and 5-30 summarize the correc tion factor results for NOx emissions. Because the Bag 1 RVP effects were found to differ between PCs and LDTs, separate estimates are given in the tables; however, no such differences could be detected for the FTP Composite or Bags 2 and 3 phases. Cold ambient temperatures increase Bag 1 NOx emissions by 25 to 30 percent depending on the vehicle group. High RVP gasoline has no direct effect on Bag 1 NOx emissions of PCs, but is found to increase LDT emissions by 18 percent at an RVP of 13 psi at all te mperatures. High RVP gasoline has adverse effects on Bag 2 and Bag 3 NOx emissions for all vehicles at all temperatures. Fuel oxygenation at the E10 level increases NOx e missions by approximately 10 percent in all FTP Bags and by larger amounts at higher oxygen contents.

### -81- Table 5-29 Correction Factor Coefficients for FTP NOx Emissions Composite Bag 1 Bag 2 Bag 3 All PCs LDTs All All T Groups 1+2 -0.00691 -0.01046 -0.01046

-- -- Groups 3+4 -0.00594 -0.00896 -0.00896 RVP Groups 1+2 0.03135 -- 0.04152 0.06290 0.04520 Groups 3+4 -- RVP · T Groups 1+2

-- -- -- -- -- Groups 3+4 -- -- -- --
OxPct 0.02361 0.01640 0.01640 0.03110 0.03620 OxPct · OxPct -- -- -- -- --



### Table 5-30 Estimated Effects of Design Va riables on FTP NOx Emissions (Compared to Design Variable Values as Stated, Percent) Design Variable Conditions Composite Bag 1 Bag 2 Bag 3

All PC LDT All All

T = 50°F Groups 1+2 T 75F->50F, RVP = 9, E0 19% 30% -- -- Groups 3+4 16% 25% -- -- RVP = 13 psi at 75°F Groups 1+2 RVP 9->13, T=75°F, E0 13% none 18% 28% 20% Groups 3+4 13% RVP = 13 psi at 50°F Groups 1+2 RVP 9->13, T=50°F, E0 13% none 18% 28% 20% Groups 3+4 13% Oxygenation at 75°F and 50°F

E10 E0->E10- E20, RVP = Any,

T = Any 9% 6% 12% 14%

E15 14% 10% 19% 22%

E20 19% 13% 26% 31%



## 5.6 Comparison of Adjustment Factors to Those in MOBILE6.2

Table 5-31 compares the CO adjustment factors estimated for this study to those currently incorporated in the MOBILE6.2 mode l. One major finding is the continued presence of an oxygenate effect in Tier 1 a nd later vehicles that reduces CO emissions on

### -82- Table 5-31 Comparison of CO Adjustment Factors to MOBILE6.2 Factors MOBILE6.2 Factors CRC E74b Factors Oxygenate Effect (Tier 1 and Later Vehicles) Normal Emitters no effect Bag 1 -8.4% per %O 2 a 

### Bag 2 -8.7% per %O 2 a 

### Bag 3 -9.5% per %O 2 

### High Emitters -5.3% per %Oxygen not tested RVP Effect (RVP 9-13) at 75°F Group 1/2 Vehicles Bag 1 4.2% per psi Bag 1 3.7% per psi 

### Bag 2 30% per psi Bag 2 18.4% per psi 

### Bag 3 26% per psi Bag 3 15.8% per psi 

### Group 3/4 Vehicles Bag 1 4.2% per psi Bag 1 3.7% per psi 

### Bag 2 30% per psi Bag 2 18.4% per psi 

### Bag 3 26% per psi Bag 3 not detected 

### RVP Effect (RVP 9-13) at 50°F Group 1/2 Vehicles Bag 1 0.7% per psi Bag 1 -3.8% per psi 

### Bag 2 5.0% per psi Bag 2 0.7% per psi 

### Bag 3 4.4% per psi Bag 3 2.5% per psi 

### Group 3/4 Vehicles Bag 1 0.7% per psi Bag 1 -3.8% per psi 

### Bag 2 5.0% per psi Bag 2 0.7% per psi 

### Bag 3 4.4% per psi Bag 3 not detected

a Oxygenate effect depends on oxygen content. Value shown is for E10.



### the order of 8% per percent oxygen conten t of the fuel. MOBILE6.2 assumes no benefit from oxygenated fuels in normal emitting Tier 1 and later vehicles. The approximately 7-9% per percent effect found here is even larger than the ~5% per percent effect assumed for high emitters in MOBILE6.2. As previously noted, none of the vehicles tested in this program were high emitters and therefore no inferences can be drawn from the data, although for inventory purposes it would be reasonable to assume that high emitters experience at least the same effect as normal emitters.

For Tier 1 and later vehicles (Groups 1 and 2), the CO emissions effects due to gasoline RVP in the range 9 to 13 psi are generally comp arable to (Bag 1) or much smaller than (Bags 2 and 3) the responses assumed in MOBILE6.2. For Tier 2 vehicles (Groups 3 and 4), this study estimates a comparable effect in Bag 1, a much smaller effect in Bag 2, and cannot detect an effect in Bag 3. The overall consequence of the revised CO RVP

### -83- adjustment factors for a fleet of in-use vehi cles will depend on the mix of vehicles in the fleet and the relative contributions of cold -start, hot-start, and running emissions.

As demonstrated in Section 4.6, this study confirms the assumpti on made in MOBILE6.2 that gasoline RVP reductions below 9 psi have little or no effect on CO emissions.

Correction factors developed in this stud y for exhaust NOx and THC emissions are compared in the following tables. As Ta ble 5-32 shows, the correction factors for

Table 5-32 Comparison of THC Adjustment Factors to MOBILE6.2 Factors MOBILE6.2 Factors CRC E74b Factors Oxygenate Effect a 

### (Tier 1 and Later Vehicles)

Normal Emitters Variable but negative a 

### Bag 1 -2.6% per %oxygen b 

### Bag 2 no effect Bag 3 no effect High Emitters Variable but negative a 

### not tested RVP Effect (RVP 9-13) at 75°F Group 1/2 Vehicles Bag 1 2.3% per psi Bag 1 no effect Bag 2 17% per psi Bag 2 7.2% per psi Bag 3 14% per psi Bag 3 2.0% per psi Group 3/4 Vehicles Bag 1 2.3% per psi Bag 1 no effect Bag 2 17% per psi Bag 2 0.2% per psi Bag 3 14% per psi Bag 3 2.0% per psi RVP Effect (RVP 9-13) at 50°F Group 1/2 Vehicles Bag 1 0.4% per psi Bag 1 no effect Bag 2 2.8% per psi Bag 2 7.2% per psi Bag 3 2.4% per psi Bag 3 2.0% per psi Group 3/4 Vehicles Bag 1 0.4% per psi Bag 1 no effect Bag 2 2.8% per psi Bag 2 0.2% per psi Bag 3 2.4% per psi Bag 3 2.0% per psi

a Oxygenate effect in MOBILE6.2 depends on the absolute level of the basic emission rate at standard conditions computed using a methodology carried over from MOBILE4.1.
b Oxygenate effects tabulated for this study are at 75°. Oxygenate is estimated to have negligible effect at 50°.

### -84- oxygenate effects on THC emissions cannot be effectively compared owing to the dependence of the MOBILE6.2 factors on the base THC emission rate of the vehicle technology group in question. For Bag 1, both MOBILE6.2 and the current study indicate declining THC emissions with increasin g oxygen content, but this study does not detect an oxygenate effect on THC emissions in Bags 2 and 3. Adjustments for RVP effects on exhaust THC emissions based on the current study are again similar to those in MOBILE6.2, with increasing RVP leading to higher THC emissions, although the Bag 2 effect seen here is larger. However, this study finds no difference in the magnitude of the effect (on a percentage basis) at 50°F compared to that at 75°F.

Table 5-33 shows that, as expected, increasi ng oxygen content leads to increased NOx emissions, despite the fact that MOBILE6.2 ig nores this effect. Directionally, the adjustment factors for RVP effects on NOx are consistent with those in MOBILE6.2, although somewhat larger in size, with NOx emissions increasing with increasing RVP.

Table 5-33 Comparison of NOx Adjustment Factors to MOBILE6.2 Factors MOBILE6.2 Factors CRC E74b Factors Oxygenate Effect (Tier 1 and Later Vehicles)

Normal Emitters No effect Bag 1 1.6% 

### per %oxygen
Bag 2 3.1% 

### per %oxygen
Bag 3 3.6% 

### per %oxygen High Emitters No effect not tested RVP Effect (RVP 9-13) at 75°F All Vehicles Bag 1 1.4% per psi Bag 1 4.2% per psi 

### Bag 2 2.8% per psi Bag 2 6.4% per psi 

### Bag 3 No effect Bag 3 4.6% per psi 

### RVP Effect (RVP 9-13) at 50°F All Vehicles Bag 1 0.2% per psi Bag 1 4.2% per psi 

### Bag 2 0.5% per psi Bag 2 6.4% per psi 

### Bag 3 No effect Bag 3 4.6% per psi



### However, this study finds no difference in the magnitude of the RVP effect (on a percentage basis) at 50°F compared to that at 75°F. The current study does, however, show Bag 3 impacts, whereas MOBILE6.2 assumes no effect.

### -85- 

## 5.7 Comparison of RVP and Oxygenate Effe cts to Those of Previous Sierra Study

As noted previously, in 2003 Sierra examin ed available CO exhaust test data at temperatures below 75°F and developed RVP and temperat ure adjustments using the same form used in this study. * 

### That study compiled data from seven test programs and extracted data from 1988-and-newer model ye ar, fuel-injected ve hicles tested at temperatures between 35° and 75°F for use in adjustment factor analysis. It was observed in that analysis that the RVP and RVP · T coefficients were significantly more uncertain than the temperature coefficient. Because the overall goal was to develop a new RVP adjustment approach, the RVP-related coefficients were defined even if not statistically significant. †



### Table 5-34 presents the RVP and temperature correction coefficients for CO exhaust from both studies for comparative purposes. The temperature coefficient from the E-74b test program is about half that of the previ ous Sierra analysis, which may be a reflection of the effects of cold temperature CO standa rds. The RVP coefficient of the E-74b test program is greater and the coefficient that defines how the RVP effect changes with temperature is also greater.

Table 5-35 presents the percent change in emissions due to reducing RVP from 11.7 psi to 9.0 psi using the equation coefficients of the two studies. Additionally, the percent change in emissions as estimated by MO BILE6.2 is presented. The RVP of 11.7 was chosen as this is the MOBILE6.2 upper limit for RVP adjustment. ‡ 

### Overall, the relative RVP effects observed in the E-74b data are dis tinctly different from those of the previous Sierra analysis. However, it should be r ecalled that the absolute (e.g., g/mi) CO emissions of the vehicles previ ously analyzed by Sierra were much higher than those of the E-74b program vehicles. In addition, at lower temperatures, the E-74b data show a reduction in CO emissions at higher RVP. Finally, both the E-74b data and previous Sierra analysis show a smaller relative impact of RVP on CO emissions than is predicted by MOBILE6.2. §

* “Review of Current and Future CO Emissions From On-Road Vehicles in Selected Western Areas,” Report No. SR03-01-01, prepared for Western States Pe troleum Association by Sierra Research, January 2003. † There is a greater degree of variability inherent in the previous Sierra analysis due to the wider variability of vehicles and test conditions reflected in the data. Only FTP-composite and matched vehicle test data were included in the analysis. ‡ The modeling limit is discussed further in Section 6 of this report. § As discussed in the 2003 Sierra report, the MOBILE6.2 RVP corrections are based on 75°F test data only, and the RVP effect is assumed to decline linearly to no effect at 45°F.

### -86- Table 5-34 Comparison of RVP and Temperature Adjust ment Equation Coefficients for FTP Composite Exhaust CO Emissions Modeling Coefficient CRC E-74b Previous Sierra (All Data) T -0.01857 -0.0355 RVP 0.07946 0.0116 RVP · T 0.00370 0.000144

Table 5-35 Estimated Impact of Reducing RVP from 11.7 to 9.0 psi on FTP Composite CO Emissions

Temperature (°F) CRC E-74b Previous Sierra (All Data) MOBILE6.2 *


### 75 -19.3% -3.1% -46.1% 65 -10.8% -2.7% -35.6% 55 -1.5% -2.3% -20.4% 45 8.9% -1.9% 0.0%

###

* MOBILE6.2 was operated for calendar year 2007 using a national default fleet mix. Trip length, vehicle soak periods, start emissions, and driving cycle adjustments were defined to simulate those characteristics of the FTP composite test cycle.

### -87- 

## 6. COMPARISON OF MOBILE6.2 AND UPDATED CO ADJUSTMENT FACTORS

This section first describes the methodolog y to incorporate the emission adjustment factors presented in the previous section in to MOBILE6.2; it then compares the estimated wintertime CO emissions inventory for Clark County (Las Vegas), Nevada obtained using the updated adjustment factors to that derived with the original factors in MOBILE6.2. The Las Vegas area was selected for this comparison for several reasons. It—along with the Phoenix, Arizona area—represents one of the two major urban areas where regulations requiring winter gasoline to contain 3.5 percent oxygen by weight and limiting RVP to 9 psi were implemented in order to reduce CO emissions from on-road vehicles. Because limited project resources precluded comparisons in both areas, it was selected over Phoenix due to the availability of the emission inventory data required to perform the comparison.



## 6.1 Methodology

MOBILE6.2 – For the Las Vegas CO inventory analysis, selected winter gasoline RVP and oxygenate scenarios were analyzed under typical winter conditions for the CO SIP evaluation years of 2006, 2010, and 2015. Emissi on factors were estimated by the U.S. EPA’s MOBILE6.2 model * 

### and combined with data on vehicle miles traveled (VMT) to yield on-road CO inventories for the study area.

The MOBILE6.2 emission factor modeling relied on input data specific to Clark County, which reflect local winter temperatures, fuel parameters, registration distributions, VMT distributions by vehicle class, VMT distributi ons by hour of day, distribution of vehicle starts by hour of day, and inspection and ma intenance (I/M) parameters. These modeling data, specific to the evaluation calendar ye ars, were those from the recent 2005 SIP revision. † 

### Hourly winter temperatures, a key assumption for the analysis, fell within the range of 42oF (minimum) and 66oF (maximum). The diurnal profiles for temperature and VMT are shown in Figure 6-1. Combining the hourly temperature profile with the hourly VMT profile showed that 70% of the VMT on the average winter day fell within the 50oF to 75oF range, making the Clark County area ideally suited for an evaluation of fuel adjustment factors at these temperatures.

* Version 6.2.03 dated September 2003. † “Carbon Monoxide State Implementation Plan Revision Las Vegas Valley Nonattainment Area Clark County, Nevada,” Clark County Department of Air Quality and Environmental Management and Clark County Board of Commissioners, October 2005.

### -88- Figure 6-1 Las Vegas Typical Winter Day Diurnal Profiles

40 45 50 55 60 65 7012:00 AM1:00 AM2:00 AM3:00 AM4:00 AM5:00 AM6:00 AM7:00 AM8:00 AM9:00 AM10:00 AM11:00 AM12:00 PM1:00 PM2:00 PM3:00 PM4:00 PM5:00 PM6:00 PM7:00 PM8:00 PM9:00 PM10:00 PM11:00 PM

Begin HourTemperature (Degrees F)

0.0% 1.0% 2.0% 3.0% 4.0% 5.0% 6.0% 7.0% 8.0%Hourly VMT (Percent of Daily Total) Temperature Hourly VMT



### Las Vegas VMT data were taken from a 2007 analysis of summer gasoline volatility control options as these represented more recent travel demand modeling since the 2005 SIP revision. * 

### Interpolation between calendar years was completed, as needed, to match the inventory years of this analysis. The VMT data used represent the urban portion of Clark County, which is also the region subject to the local I/M program requirements. Average daily VMT estimates used in this evaluation were 40,050,285 for 2006; 50,608,417 for 2010; and 59,804,322 miles for 2015.

As noted above, winter gasoline sold in Clark County is currently subject to RVP limits as well as specifications for oxygenate conten t. In addition, sulfur and aromatic content restrictions apply. The current wintertime gasoline fuel requirements in Clark County are summarized in Table 6-1; the 2006 winter Clark County gasoline properties are summarized in Table 6-2. These data we re taken from the Winter 2006 Alliance of Automobile Manufacturers (AAM) Fuel Survey Data. †

* “Demonstration of the Necessity of Regulations Requiring 7.0 PSI RVP Gasoline in Clark County, Nevada as an Ozone Control Strategy,” Sierra Research, November 2007. † “Alliance of Automobile Manufacturers North American Fuel Survey Motor Gasoline Winter 2006,” Alliance of Automobile Manufacturers, 2006.

### -89- Table 6-1 Wintertime Gasoline Fuel Requirements for Clark County Fuel Property Standard Reid Vapor Pressure (RVP) Max 9.0 psi (10.0 psi for fuel with 9+ vol % EtOH) Sulfur Content Max 80 ppmw; Flat limit of 40 ppmw Aromatic Content Max 30 vol %; Flat limit of 25 vol % Oxygen Content Min 3.5 wt %

Table 6-2 Winter 2006 Gasoline Parameters Fuel Property Clark County Gasoline Methyl Tertiary Butyl Ether (MTBE) (wt% oxygen) 0 Ethyl Tertiary Butyl Ether (ETBE) (wt% oxygen) 0 Ethanol (wt% oxygen) 3.47 Tertiary Amyl Methyl Ether (TAME) (wt% oxygen) 0 Sulfur (ppm) 31 RVP (psi) 8.8 E200 (%) 46.4 E300 (%) 78.7 Aromatics (vol%) 20.2 Olefins (vol%) 6.7 Benzene (vol%) 0.60

For the fuel scenarios, both RVP and oxygenate levels were varied. A total of nine fuel scenarios were modeled (the unique combin ations of three RVP and three oxygenate levels) by including the following parameters:

 RVP of 9, 11.7, and 13.3 psi; and

 Oxygen content of 0, 2.7, and 3.5 weight percent.

The RVP levels selected reflect the curr ent 9 psi limit, the maximum RVP adjustment currently allowed in MOBILE6.2 (11.7 psi), a nd the maximum RVP of the fuels in this test program (13.3 psi). * 

### The oxygenate levels were chosen on the basis of the minimum content required for serious CO nonattainment areas (2.7 weight percent), the maximum

* 11.7 psi is the upper bound for gasoline volatility effects in the U.S. EPA MOBILE6.2 model. This level represents the highest RVP of the test fuels from which the model’s gasoline volatility algorithms are based. As such, the standard version of the model treats any gasoline with volatility over 11.7 psi as 11.7 psi fuel.

### -90- level currently allowed (3.5 weight percen t), and the elimination of an oxygenate requirement (0 weight percent). *



### Code Modifications to Incorporate Adjustment Factors and Provide for Comparisons – Two versions of MOBILE6.2 were used in th e inventory analysis of the nine fuel scenarios. One was the standard U.S. EPA model with the 11.7 psi RVP upper limit raised to 13.3 psi, and the second was develope d by modifying the source code to updatethe treatment of temperature, volatility, and oxygenate effects as measured in the CRC E74b test data. A summary of th ese models is outlined below.

 U.S. EPA MOBILE6.2 – This is the standard regulatory model currently available from the U.S. EPA. The maximum volatility effect of 11.7 psi was modified for this project by raising it to 13.3 psi. This means that the model’s existing RVP correction algorithms were extrapolated to 13.3 psi, and the correction equation coefficients were unchanged.

 Updated Adjustment Factor Version of MOBILE6.2 – The U.S. EPA model was modified with updated Tier 1 and later vehicle adjustment factors for varying temperature, gasoline volatility, and oxygenate levels based on the CRC E-74b test program. The maximum volatility eff ect of 11.7 psi was raised to the test program maximum of 13.3 psi. Note that although none of the vehicles in the test program were “high emitters,” the oxygenate adjustment factors developed here were also applied to vehicles in that emissions regime. †



### For modeling volatility effects below 75oF, th e U.S. EPA version of MOBILE6.2 applies a multiplicative adjustment factor to correct for gasoline volatility in excess of 9.0 psi (where the adjustment factor equals unity at 9.0 psi). The exponential equation used to define the multiplicative adjustment factor below 75oF is as follows:



##          

   30 45T 9RVP RVPEXP RVP COEFF ADJ



### Where RVP ADJ 

### = RVP adjustment (unitless multiplier), RVP COEFF 

### = RVP equation coefficient (psi -1 

### ), RVP = RVP (psi), and T = Temperature ( o 

### F).

* Because Clark County is still designat ed as a “serious” nonattainment area with respect to attainment of the eight-hour CO NAAQS, winter gasoline is still required by the Clean Air Act to contain at least 2.7% oxygen by weight. † The revised Tier 1 and later vehicle oxygenate corrections (for normal emitters) were found to be greater than the existing model assumption for high emitters (a value carried over from Tier 0 vehicles). Engineering judgment was applied in which the oxygenate effect for high emitters of a given vehicle technology would not be less than those estimated for normal emitters. Therefore, the Tier 1 and later vehicle high emitter oxygenate corrections were modified to equal those estimated for normal emitters.

### -91- However, an alternate form of the RVP adju stment equation (that used by the model for temperatures over 75oF) was used as the basi s for the updated adjustment factor version of MOBILE6.2. This equation, which combines both temperature and RVP adjustments, is shown below. The equation also incl udes a combined temperature and RVP term allowing for a varying RVP effect as temperature changes. *



##           75T9RVP RT75TT9RVP RVPEXP RVP&T COEFF COEFF COEFF ADJ   



### Where T & RVP ADJ 

### = Combined temperature and RVP adjustment (unitless multiplier), RVP COEFF 

### = RVP term coefficient (psi -1 

### ), T COEFF 

### = Temperature term coefficient ( o 

### F -1 

### ), RT COEFF 

### = Combined RVP and temperature term coefficient ( o 

### F -1 

### psi -1 

### ), RVP = RVP (psi), and T = Temperature ( o 

### F).

The updated equation coefficients (RVP COEFF 

### , T COEFF 

### , and RT COEFF 

### ) were programmed directly into the source code, including c onditional statements needed to make proper vehicle technology distinctions (i.e., keep the Tier 0 code unchanged and continuing to use the existing U.S. EPA modeling approach ). Additional minor code modifications were made so that additional vehicle charac teristics were available (for model year and vehicle class) such that vehi cle technologies could be corr ectly identified. Lastly, the model’s existing temperature corrections for Tier 1 and later vehicles were deactivated to avoid double counting the temperature corre ction, given that the new equation and coefficients in the updated model encompa ss both temperature and volatility corrections.

For modeling oxygenate effects, MOBILE6.2 a pplies a multiplicative adjustment factor to correct for oxygen levels between zero and 3.5 weight percent (where the adjustment factor equals unity at zero oxygen cont ent). The equation used to define the multiplicative adjustment is as follows:

        100 OXY OXY 1OXY COEFF ADJ



### Where OXY ADJ 

### = OXY adjustment (unitless multiplier), OXY COEFF 

### = OXY equation coefficient (% exhaust impact/wt. % oxygen), and OXY = Weight percent oxygen (in gasoline-oxygenate blend).

* This equation is improved over the default MOBILE6. 2 equation because it allows for the evaluation of all coefficients (temperature and RVP) based on the actual test data and because it does not simply assume a linear decay in the 75oF RVP effect between 75o and 45o as computed by the U.S. EPA model.

### -92- The updated oxygenate eff ect coefficients (OXY COEFF 

### ) were programmed directly into the source code, including conditional stat ements needed to make proper vehicle technology distinctions. Add itional code modifications were made so that FTP phasespecific coefficients could be applied. This differs from the regulatory version of the model in which the coefficients are unifo rm for all FTP phases (i.e., based on FTP composite test results). Combining the FTP phase-specific corrections into start and running exhaust corrections was modele d on the similar approach developed for temperature and volatility by the U.S. EPA. *†



### It should be noted that because the fuel s cenarios include the case of 9.0 psi and zero oxygen content (instances where the adjus tment factors for these two effects become unity), the only difference in predicted emi ssion rates between model versions for this specific case becomes the temperature correction adjustments. This allows for a quantification of the temperature adjustment differences alone, independent of the other fuel adjustments.



## 6.2 Results

The winter on-road CO emission inventor ies for Las Vegas obtained using MOBILE6.2 and the updated adjustment factors are presen ted in Table 6-3 for each of the nine combinations of RVP and oxygen content, for each of the three analysis years. The results are also presented graphically in Figures 6-2 through 6-4.

As can be seen from the data in Table 6- 3 and more easily in Figure 6-2, use of the updated adjustment factors for oxygenat e content has a profound impact on the Las Vegas CO inventory. Figure 6-2 shows only the oxygenate effect at the three oxygenate levels analyzed for gasoline at 9.0 psi RVP for th e three analysis years. The first point is that the predicted reduction in CO emissions associated with moving from zero to 3.5% oxygen by weight is more than 3 times greater using the updated adjustments than is

* In MOBILE6.2, exhaust emissions are estimated for two components: the running LA4 plus the incremental start offset; however, correction factors within MOBILE6.2 continue to be applied on an FTP phase-specific basis, as they were originally derived in MOBILE5 and earlier versions. The MOBILE6.2 model applies both Phase 1 and Phase 3 corrections to the incremental start exhaust (depending on the length of the vehicle soak period); the model applies a weighted Bag 2 and Bag 3 correction to the running LA4 exhaust. See the MOBILE6.2 technical documentation “Exhaust Emission Temperature Correction Factors for MOBILE6: Adjustments for Engine Start and Running LA4 Emissions for Gasoline Vehicles (M6.STE.004)” for an elaboration and justification of this approach as well as a discussion of its shortfalls. † Consideration was given to whether phase-specific corrections should be retained or alternatively whether corrections should be converted into “start increments ” and “running exhaust” using the regression analysis of the U.S. EPA for the development of exhaust basic emission rates. The concerns with the alternative approach were (1) that the U.S. EPA analysis was based on predominately high-emitting Tier 0 vehicles and was not representative of the CRC test fleet, and (2) that the regression coefficients should not remain constant across conditions that include varying temperature and fuel parameters. For these reasons, and for maintaining consistency with MOBILE6.2, the phase-specific correction method was retained.

### -93- Table 6-3 Comparison of Las Vegas Winter On-R oad CO Inventory Based on MOBILE6.2 and Updated Adjustment Factors (tons per day)

RVP MOBILE6.2 Updated Ad justment Factors 0 % Oxygen 2.7% Oxygen 3.5% Oxygen 0 % Oxygen 2.7% Oxygen 3.5% Oxygen 2006 9 473 443 434 392 319 301 11.7 559 523 513 440 359 339 13.3 643 602 590 449 366 345 2010 9 480 459 453 368 294 277 11.7 566 540 532 402 322 303 13.3 650 620 611 411 329 310 2015 9 475 459 455 341 268 252 11.7 556 537 531 360 284 267 13.3 635 613 607 367 290 272

Figure 6-2 Winter On-Road CO Emission Inve ntory for Clark County, Nevada 9 RVP Gasoline

200 250 300 350 400 450 500

200 250 300 350 400 450 500

2006 2010 2015 2006 2010 2015COTPDCOTPD



### YEAR YEAR 

### MOBILE 6.2 Updated Adjustments

0% Oxygen
2.7% Oxygen
3.5% Oxygen

### -94- Figure 6-3 2010 Winter On-Road CO Emission In ventory for Clark County, Nevada as a Function of RVP

200 250 300 350 400 450 500 550 600 650 700

200 250 300 350 400 450 500 550 600 650 700

9 11.7 13.3 9 11.7 13.3COTPDCOTPD



### RVP RVP 

### 2010 MOBILE 6.2 2010 Updated Adjustments

0% Oxygen
2.7% Oxygen
3.5% Oxygen



### Figure 6-4 2010 Winter On-Road CO Emission In ventory for Clark County, Nevada as a Function of Oxygenate Level

200 250 300 350 400 450 500 550 600 650 700

200 250 300 350 400 450 500 550 600 650 700

0 2.7 3.5 0 2.7 3.5COTPDCOTPD



### % OXYGEN % OXYGEN 

### 2010 MOBILE 6.2 2010 Updated Adjustments

9 RVP
11.7 RVP
13.3 RVP

### -95- predicted by MOBILE6.2. The second point is that because the updated adjustments show oxygen impacts in advanced technology vehicles, the trend in CO emissions over time at a given oxygen content decreases, rather than increases as predicted by MOBILE6.2.

Figures 6-2 and 6-3 compare the 2010 invent ories generated using MOBILE6.2 and the updated adjustment factors as a function of RV P for constant oxygenate levels and as a function of oxygenate content for constant RV P, respectively. As shown in Figure 6-2, the updated adjustment factors show significantly smaller RVP impacts, as evidenced by the smaller slopes of the lines. Indeed, th e updated adjustment model results in a 45 percent reduction in the RVP effect in 2010 for this modeling scenario. Figure 6-3 again highlights the large differences between the MOBILE6.2 and updated oxygenate adjustments.

Moreover, the two model results for 0% oxygen at 9.0 psi can be compared to illustrate the differences in temperature corrections (as reported in Table 6-3). In 2010, the updated adjustment model inventory of 368 tons per day is 23 percent less than the 480 tons per day inventory using the standard MOBILE6.2. Both MOBILE6.2 models estimate an increase in CO for temperatures below 75oF; however, the increase in CO at lower temperatures is significantly less in the updated adjustments model.

Finally, one additional comparison of the E-74b data to MOBILE6.2 was performed. In this comparison, FTP composite CO emission rates at standard conditions from the E-74b program were compared against the MO BILE6.2 output emission rates at similar conditions. In order to perform this co mparison, MOBILE6.2 was run at 75°F, 9.0 psi, and 0 wt% oxygen for calendar year 2006. * 

### The individual test ve hicles were matched to MOBILE6.2 emission factor predictions based on vehicle weight class and model year, and the results were averaged over the four te chnology groups examined for this study. The four results are shown in Table 6-4. No tably, the Tier 1 technology group and the model prediction are the most similar (a 16 percent difference). However, the improvement in CO exhaust with successive technology groups is much greater in the test fleet (relative to that predicted by the model). This sample population suggests that CO emission rates are declining more quick ly than what is assumed in MOBILE6.2.

* Trip length, vehicle soak periods, start emissions and driving cycle adjustments were defined to simulate those characteristics of the FTP composite test cycle. Moreover, the high emitter fraction of the fleet was forced to zero (i.e., 100 percent of the fleet was normal emitters).

### -96- Table 6-4 Comparison of E-74b and MOBILE6.2 Emission Rates FTP Composite CO Exhaust Emissions at Standard Conditions (grams per mile)

Technology Group MOBILE6.2 CRC E-74b Percent Difference Tier 1 5.8 4.9 -16% NLEV 2.2 1.3 -41% Tier 2, Enhanced Evaporative 1.3 0.7 -50% Tier 2, Near Zero Evaporative 1.2 0.2 -81%

###

## APPENDIX A
Sulfur Removal Protocol Used in Testing

### A-1 Sulfur Removal Protocol Used in Testing

This procedure is designed to cause the vehicl e to transiently run rich at high catalyst temperature, so as to remove accumulated su lfur from the catalyst via hydrogen sulfide formation. The drive trace is shown below the descriptive protocol. The catalyst inlet temperature and the exhaust air/fuel (A/F) ratio must be monitored during this procedure. It is required to demonstrate that the catalyst inlet temperature exceeds 700°C during the wide-open throttle (WOT) accelerations and that rich air/fuel mixtures are achieved during WOT. If these parameters ar e not achieved, increased loading on the dynamometer should be added for this protoc ol (but not during the emissions test).

1. Drive the vehicle from idle to 55 mph and hold speed for 5 minutes (to bring catalyst to full working temperature). 2. Reduce vehicle speed to 30 mph and hold speed for one minute. 3. Accelerate at WOT for a minimum of 5 sec onds, to achieve a speed in excess of 70 mph. Continue WOT above 70 mph, if necessary to achieve 5-second acceleration duration. Hold the peak speed for 15 seconds and then decelerate to 30 mph. 4. Maintain 30 mph for one minute. 5. Repeat steps 3 and 4 to achieve 5 WOT excursions. 6. One sulfur removal cycle has been completed. 7. Repeat steps 1 to 5 for the second sulfur removal cycle. 8. The protocol is complete if the necessary parameters have been achieved.

WOT Acceleration must exceed 5 seconds duration, Extended by peak speed greater than 70 mph

0 20 40 60 80

0 5 10 15 20 25Vehicle Speed, mph

Test Time, minutes Monitor Catalyst inlet Temperature and Exhaust A/F Ratio. Demonstrate that Cat. In. Temp > 700C and A/F Ratio goes rich.

## APPENDIX B

Additional Vehicle and Test In formation and Emissions Data

### B-1 Test Vehicle VIN and Engine/Evap Family
Veh No Model Year Make VIN Engine Family Evaporative Family

001 1994 Chevrolet 2G1WL54T0R1115291 R1G3.1V7GAEA R1G1058AYM0A 002 1996 Ford 1FALP52U6TG137967 TFM3.0V8GKEK TFM1115AYMEB 003 1995 Jeep 1J4FJ67S6SL657625 SCR4.078GAEA SCR1058AYP0N

004 1999 Honda AHGCG5651XA016867 XHNXV02.3PA3 XHNXR0130AAA 005 2001 Toyota 1NXBR12E81Z533653 1TYXV01.8FFA 1TYXR0115AK1 006 2002 Nissan 1N4AL11D42C224558 2NSXV02.5D5A 2NSXR0120RCB 007 2001 Dodge 2B4GP44361R210600 1CRXT03.32DP 1CRXR0165XAA 008 2002 Chevrolet 1GNDS13S422364628 2GMXT04.2185 2GMXR0175922

009 2004 Dodge 1B3EL36X54N278471 4CRXV02.4VE0 4CRXR0130GBA 010 2004 Chevrolet 2G1WF52E049104510 4GMXV03.8042 4GMXR0124919 011 2004 Toyota 4T1BF30K94U575699 4TYXV03.0WMA 4TYXR0130A11 012 2006 Ford 1FAFP53U16A148832 6FMXV03.0VEY 6FMXR0185GAK 013 2004 Dodge 1D7HA16N94J136979 4CRXT04.75J0 4CRXR0218GDH 014 2004 Ford 1FMYU02174KA86202 4FMXT03.01FE 4FMXR0110BBE 015 2004 Toyota JTEDPZ1AZ40035821 4TYXT03.3PEM 4TYXR0165P21B-2Test Results - Vehicle 001Bag 1Bag 2Test Fuel Temp NMHC HC CO NOX CO2 MPG NMHC HCCO NOX CO2 MPG4831 AsRcvd 75 0.786 0.841 10.35 1.523 423.9 20.1 0.073 0.117 3.53 0.537 426.4 20.65060 1 50 0.935 1.050 10.67 1.993 469.2 17.4 0.073 0.110 2.22 0.755 451.3 18.75034 2 50 0.857 0.965 11.01 1.817 452.0 18.0 0.058 0.103 2.49 0.841 455.9 18.55082 3 50 0.945 1.078 14.74 1.830 474.4 17.3 0.063 0.117 2.37 0.757 465.0 18.55165 4 50 1.132 1.274 16.92 2.552 476.7 16.2 0.055 0.095 1.64 0.868 455.1 17.95072 5 50 0.925 1.057 14.35 1.871 459.9 17.7 0.096 0.146 4.05 0.808 458.4 18.55138 1 75 0.742 0.838 7.41 1.784 443.9 18.6 0.058 0.098 2.42 0.749 451.4 18.75010 2 75 0.801 0.911 10.34 1.487 463.4 17.6 0.102 0.175 6.39 0.608 464.0 17.95154 3 75 0.829 0.944 10.90 1.648 435.1 19.0 0.115 0.173 5.48 0.597 440.9 19.35131 4 75 0.716 0.807 8.19 1.892 448.7 17.7 0.051 0.097 2.73 0.791 449.5 18.05148 5 75 0.866 0.986 14.07 1.728 438.4 18.6 0.128 0.197 7.46 0.782 447.6 18.75089 6 75 0.900 1.027 12.63 1.713 441.6 18.9 0.058 0.109 2.29 0.801 454.0 19.25097 6 75 0.903 1.023 10.74 1.755 452.1 18.6 0.061 0.108 2.25 0.818 466.5 18.75112 7 75 0.873 0.987 10.07 1.701 452.6 18.2 0.071 0.118 2.37 0.667 462.8 18.35119 7 75 0.814 0.924 9.37 1.742 453.9 18.2 0.059 0.106 2.66 0.677 459.4 18.5Bag3 FTPCompositeTest Fuel Temp NMHC HC CO NOX CO2 MPG NMHC HCCO NOX CO2 MPG4831 AsRcvd 75 0.158 0.193 3.82 1.042 350.9 24.9 0.244 0.288 5.03 0.880 405.2 21.55060 1 50 0.160 0.208 3.29 1.042 386.7 21.7 0.276 0.332 4.27 1.091 437.2 19.25034 2 50 0.124 0.163 3.31 0.970 379.3 22.1 0.242 0.298 4.48 1.079 434.1 19.35082 3 50 0.186 0.239 3.90 1.102 387.6 22.0 0.280 0.350 5.36 1.075 445.7 19.05165 4 50 0.186 0.236 4.73 1.345 378.1 21.2 0.314 0.378 5.66 1.348 438.4 18.35072 5 50 0.205 0.274 6.25 1.200 389.4 21.5 0.298 0.371 6.79 1.137 439.8 19.15138 1 75 0.125 0.165 5.22 1.076 386.6 21.6 0.218 0.270 4.23 1.054 432.1 19.45010 2 75 0.237 0.308 11.65 0.716 378.2 21.4 0.285 0.365 8.66 0.820 440.3 18.75154 3 75 0.147 0.195 4.40 0.955 377.3 22.5 0.272 0.339 6.31 0.913 422.2 20.05131 4 75 0.179 0.236 5.35 1.237 384.3 20.8 0.224 0.282 4.58 1.142 431.4 18.65148 5 75 0.329 0.414 14.43 0.870 365.6 22.1 0.336 0.420 10.75 1.002 423.2 19.55089 6 75 0.167 0.215 3.58 1.034 387.2 22.4 0.263 0.329 4.79 1.054 433.1 19.95097 6 75 0.153 0.209 6.05 1.200 391.8 21.9 0.261 0.326 5.05 1.117 443.0 19.55112 7 75 0.178 0.230 5.68 1.121 379.1 22.0 0.267 0.329 4.87 1.006 437.7 19.25119 7 75 0.177 0.234 5.61 0.959 388.1 21.5 0.248 0.311 4.86 0.976 438.7 19.1B-3Test Results - Vehicle 002Bag 1Bag 2Test Fuel Temp NMHC HC CO NOXCO2 MPG NMHC HC CO NOX CO2 MPG4784 AsRcvd 75 0.418 0.469 4.96 0.768 398.0 21.9 0.025 0.057 1.22 0.318 417.8 21.24903 1 50 0.555 0.664 10.37 0.862 431.2 19.0 0.030 0.068 1.14 0.362 436.0 19.54816 2 50 0.544 0.650 11.47 0.845 426.1 19.1 0.013 0.056 1.16 0.334 416.7 20.34827 3 50 0.562 0.680 14.55 0.732 409.8 19.9 0.002 0.039 1.05 0.301 420.7 20.54836 4 50 0.673 0.803 18.73 1.116 411.5 18.5 0.029 0.057 0.51 0.349 422.6 19.34926 5 50 0.532 0.645 12.38 0.824 413.9 19.8 0.008 0.036 1.26 0.346 431.1 19.94938 1 75 0.431 0.515 3.96 0.751 394.9 21.2 0.029 0.066 0.83 0.385 423.1 20.14880 2 75 0.410 0.486 5.23 0.698 390.3 21.3 0.031 0.055 0.84 0.304 418.1 20.34957 3 75 0.428 0.520 6.15 0.743 400.2 21.1 0.010 0.050 1.07 0.349 424.1 20.34949 4 75 0.359 0.439 4.32 0.780 396.5 20.3 0.012 0.048 0.63 0.406 418.4 19.54890 5 75 0.434 0.518 7.26 0.733 392.3 21.3 0.021 0.053 1.07 0.303 405.5 21.24982 6 75 0.430 0.516 5.42 0.798 398.9 21.5 0.020 0.055 0.65 0.313 418.0 21.04990 6 75 0.497 0.596 6.84 0.818 402.3 21.2 0.017 0.053 1.09 0.340 419.7 20.94964 7 75 0.406 0.496 5.10 0.782 398.3 21.0 0.030 0.070 0.81 0.387 419.7 20.34972 7 75 0.400 0.487 5.31 0.768 400.8 20.8 0.030 0.069 0.90 0.352 424.1 20.1Bag3 FTPCompositeTest Fuel Temp NMHC HC CO NOXCO2 MPG NMHC HC CO NOX CO2 MPG4784 AsRcvd 75 0.123 0.162 1.71 0.469 331.2 26.6 0.133 0.171 2.13 0.453 389.9 22.64903 1 50 0.080 0.129 1.58 0.521 337.5 25.1 0.153 0.208 3.17 0.509 408.0 20.64816 2 50 0.075 0.121 1.40 0.522 332.4 25.4 0.140 0.197 3.36 0.491 395.5 21.24827 3 50 0.097 0.148 1.71 0.468 329.1 26.1 0.144 0.202 4.03 0.436 393.3 21.64836 4 50 0.078 0.123 1.39 0.506 328.0 24.8 0.176 0.230 4.53 0.551 394.4 20.44926 5 50 0.090 0.134 1.56 0.570 338.6 25.2 0.139 0.189 3.65 0.507 402.1 21.14938 1 75 0.074 0.120 1.50 0.502 335.0 25.3 0.125 0.174 1.67 0.493 393.1 21.54880 2 75 0.066 0.112 1.48 0.484 324.0 26.1 0.119 0.160 1.92 0.435 386.5 21.84957 3 75 0.079 0.125 1.49 0.446 335.8 25.6 0.116 0.168 2.24 0.457 394.9 21.74949 4 75 0.069 0.116 1.41 0.501 334.0 24.3 0.100 0.148 1.61 0.510 390.7 20.84890 5 75 0.101 0.133 1.76 0.424 320.4 26.6 0.128 0.172 2.54 0.426 379.4 22.54982 6 75 0.159 0.208 1.59 0.571 330.1 26.4 0.143 0.192 1.90 0.484 390.0 22.44990 6 75 0.094 0.143 1.58 0.504 346.3 25.2 0.138 0.190 2.42 0.484 395.9 22.04964 7 75 0.086 0.135 1.50 0.483 337.1 25.2 0.124 0.176 1.89 0.495 392.6 21.64972 7 75 0.081 0.127 1.52 0.527 335.5 25.3 0.121 0.172 1.98 0.486 395.0 21.5B-4Test Results – Vehicle 003Bag 1Bag 2Test Fuel Temp NMHC HC CO NOXCO2 MPG NMHC HC CO NOX CO2 MPG4975 AsRcvd 75 1.149 1.267 12.29 2.988 462.1 18.3 0.423 0.533 7.69 1.837 501.2 17.35001 1 50 1.134 1.344 14.11 2.274 489.7 16.5 0.167 0.278 2.10 0.751 532.0 15.95118 2 50 1.140 1.310 10.33 3.260 476.5 17.1 0.272 0.396 4.77 1.321 520.3 16.15035 3 50 1.176 1.381 15.14 2.629 490.9 16.7 0.224 0.345 3.87 0.930 535.0 16.05128 4 50 1.279 1.484 12.96 3.661 485.1 16.1 0.214 0.332 3.99 1.429 524.6 15.45055 5 50 1.343 1.570 18.34 2.674 486.0 16.6 0.304 0.432 5.58 0.975 526.4 16.15005 1 75 0.932 1.079 7.93 2.146 463.6 17.8 0.209 0.328 2.67 0.676 523.7 16.15075 2 75 1.091 1.251 9.92 2.917 470.1 17.4 0.326 0.446 4.94 1.009 517.0 16.25046 3 75 1.039 1.199 10.33 2.290 467.1 17.8 0.282 0.407 4.55 0.732 522.1 16.35021 4 75 0.779 0.901 6.43 2.106 459.6 17.3 0.165 0.260 1.54 0.681 506.2 16.15013 5 75 1.034 1.194 11.22 2.036 455.2 18.1 0.401 0.545 6.32 0.679 505.9 16.75065 6 75 1.148 1.330 11.92 2.325 477.6 17.6 0.249 0.383 4.41 0.779 519.1 16.75068 6 75 1.036 1.215 10.43 2.338 461.0 18.3 0.259 0.388 4.75 0.944 526.6 16.45096 7 75 1.075 1.247 9.53 2.973 474.1 17.4 0.266 0.396 4.19 1.291 523.9 16.15103 7 75 1.027 1.214 9.41 3.059 472.0 17.5 0.269 0.380 4.49 1.203 514.2 16.4Bag3 FTPCompositeTest Fuel Temp NMHC HC CO NOXCO2 MPG NMHC HC CO NOX CO2 MPG4975 AsRcvd 75 0.712 0.796 8.85 3.183 407.9 21.0 0.653 0.757 8.96 2.446 467.5 18.45001 1 50 0.547 0.664 4.51 2.294 420.9 19.8 0.473 0.606 5.26 1.492 492.6 17.05118 2 50 0.614 0.726 5.80 2.992 412.7 20.1 0.547 0.677 6.21 2.184 481.6 17.35035 3 50 0.624 0.744 5.97 2.699 427.1 19.7 0.532 0.670 6.79 1.770 496.1 17.05128 4 50 0.538 0.652 5.40 3.120 411.2 19.4 0.524 0.659 6.24 2.357 485.2 16.55055 5 50 0.626 0.748 6.73 2.513 418.8 20.0 0.608 0.755 8.55 1.751 488.4 17.15005 1 75 0.535 0.654 4.88 1.998 410.7 20.3 0.449 0.574 4.37 1.345 480.2 17.55075 2 75 0.673 0.794 7.56 2.542 410.3 20.1 0.580 0.709 6.70 1.828 477.9 17.45046 3 75 0.593 0.702 5.73 2.158 412.2 20.5 0.524 0.653 6.08 1.448 480.5 17.65021 4 75 0.472 0.582 3.84 2.016 407.5 19.7 0.377 0.482 3.19 1.345 469.3 17.25013 5 75 0.736 0.871 8.50 2.157 404.4 20.5 0.625 0.770 7.94 1.369 467.4 17.95065 6 75 0.588 0.720 6.23 2.219 411.8 20.8 0.529 0.672 6.47 1.496 480.9 17.95068 6 75 0.602 0.719 6.44 2.330 414.7 20.6 0.515 0.651 6.39 1.615 482.2 17.85096 7 75 0.624 0.752 6.07 2.791 413.2 20.1 0.532 0.671 5.82 2.053 483.1 17.35103 7 75 0.575 0.684 5.80 2.854 413.1 20.2 0.510 0.636 5.87 2.041 477.6 17.5B-5Test Results - Vehicle 004Bag 1Bag 2Test Fuel Temp NMHC HC CO NOXCO2 MPG NMHC HC CO NOX CO2 MPG4896 AsRcvd 75 0.257 0.260 3.11 0.409 343.5 25.5 0.000 0.008 0.94 0.017 338.9 26.25347 1 50 0.325 0.391 4.05 0.816 389.8 21.5 0.014 0.025 1.13 0.023 373.5 22.75392 2 50 0.343 0.404 3.56 0.767 382.3 21.9 0.016 0.028 1.09 0.039 366.9 23.15416 3 50 0.333 0.399 6.75 0.558 387.4 21.7 0.005 0.020 1.26 0.031 367.9 23.45371 4 50 0.308 0.371 3.28 0.812 385.8 20.9 0.006 0.020 0.67 0.016 370.7 22.05378 5 50 0.329 0.390 6.21 0.537 381.7 22.0 0.010 0.024 1.25 0.053 367.3 23.35408 1 75 0.202 0.245 2.72 0.456 357.7 23.5 0.014 0.024 1.08 0.003 358.7 23.75398 2 75 0.250 0.301 3.11 0.430 360.7 23.2 0.012 0.028 1.50 0.011 365.1 23.25357 3 75 0.204 0.247 3.60 0.391 356.4 23.9 0.005 0.026 1.35 0.009 357.8 24.15344 4 75 0.189 0.228 2.25 0.451 363.7 22.3 0.011 0.019 0.54 0.010 362.9 22.55363 5 75 0.310 0.370 5.13 0.352 359.2 23.4 0.018 0.033 1.36 0.015 358.0 23.95350 6 75 0.198 0.239 4.28 0.325 358.3 24.1 0.006 0.031 1.96 0.020 367.6 23.75353 6 75 0.266 0.321 4.93 0.389 361.9 23.8 0.014 0.032 1.26 0.021 366.2 23.95333 7 75 0.243 0.292 2.82 0.431 363.6 23.2 0.010 0.025 1.20 0.009 357.6 23.85335 7 75 0.203 0.247 2.58 0.442 363.3 23.3 0.008 0.024 0.88 0.028 363.1 23.5Bag3 FTPCompositeTest Fuel Temp NMHC HC CO NOXCO2 MPG NMHC HC CO NOX CO2 MPG4896 AsRcvd 75 0.001 0.014 0.76 0.041 285.9 31.0 0.054 0.062 1.34 0.105 325.3 27.25347 1 50 0.007 0.022 0.70 0.066 328.2 25.9 0.077 0.100 1.62 0.199 364.4 23.25392 2 50 0.014 0.027 0.71 0.035 315.7 26.9 0.083 0.105 1.50 0.189 356.0 23.75416 3 50 0.003 0.017 0.84 0.033 321.3 26.9 0.073 0.098 2.28 0.141 359.2 23.95371 4 50 0.005 0.019 0.65 0.060 317.2 25.7 0.068 0.093 1.21 0.193 359.2 22.75378 5 50 0.012 0.027 0.87 0.066 313.6 27.4 0.077 0.101 2.17 0.157 355.5 24.05408 1 75 0.009 0.022 0.71 0.039 311.5 27.3 0.051 0.069 1.32 0.107 345.5 24.55398 2 75 0.012 0.026 0.95 0.041 316.9 26.7 0.061 0.084 1.68 0.106 351.0 24.15357 3 75 0.012 0.027 1.10 0.054 311.2 27.7 0.048 0.072 1.75 0.100 344.7 24.95344 4 75 0.011 0.024 0.68 0.043 320.0 25.5 0.048 0.064 0.93 0.111 351.3 23.25363 5 75 0.015 0.028 1.25 0.034 316.8 27.0 0.078 0.102 2.11 0.090 346.9 24.65350 6 75 0.018 0.034 1.41 0.059 319.1 27.4 0.049 0.075 2.29 0.094 352.3 24.75353 6 75 0.025 0.038 1.32 0.062 316.3 27.6 0.069 0.093 2.04 0.109 351.6 24.85333 7 75 0.010 0.023 0.67 0.034 319.6 26.7 0.058 0.080 1.39 0.103 348.4 24.45335 7 75 0.014 0.025 0.76 0.054 318.5 26.8 0.050 0.071 1.20 0.121 351.0 24.2B-6Test Results - Vehicle 005Bag 1Bag 2Test Fuel Temp NMHC HC CO NOXCO2 MPG NMHC HC CO NOX CO2 MPG4729 AsRcvd 75 0.261 0.282 2.69 0.341 304.9 28.7 0.039 0.058 1.14 0.070 288.3 30.74755 1 50 0.360 0.423 5.08 0.349 326.8 25.4 0.002 0.008 0.48 0.070 310.2 27.44759 2 50 0.376 0.448 4.85 0.326 325.4 25.5 0.022 0.042 0.73 0.072 314.9 26.94802 3 50 0.338 0.410 5.55 0.309 320.5 26.2 0.020 0.035 0.27 0.134 301.8 28.74747 4 50 0.416 0.484 4.09 0.362 325.6 24.6 0.026 0.047 0.75 0.038 310.0 26.34821 5 50 0.335 0.404 5.53 0.365 329.0 25.4 0.014 0.030 0.62 0.072 310.9 27.64776 1 75 0.218 0.266 2.58 0.326 301.9 27.8 0.028 0.037 0.45 0.116 303.9 28.04782 2 75 0.238 0.285 3.20 0.295 309.9 27.0 0.027 0.062 1.65 0.066 307.3 27.54733 3 75 0.230 0.280 3.51 0.272 302.2 28.1 0.021 0.036 0.69 0.040 305.3 28.34767 4 75 0.220 0.257 2.62 0.310 313.7 25.7 0.016 0.026 0.42 0.051 307.9 26.54808 5 75 0.212 0.272 3.48 0.255 301.3 28.0 0.025 0.036 0.69 0.090 301.2 28.54845 6 75 0.209 0.256 3.17 0.295 307.3 28.1 0.006 0.017 0.39 0.105 309.4 28.44855 6 75 0.223 0.273 3.60 0.260 300.6 28.7 0.019 0.036 0.66 0.059 298.7 29.44870 7 75 0.217 0.264 3.08 0.282 301.4 27.9 0.011 0.026 0.32 0.077 300.6 28.44875 7 75 0.210 0.256 2.90 0.314 303.6 27.7 0.007 0.014 0.22 0.096 306.6 27.9Bag3 FTPCompositeTest Fuel Temp NMHC HC CO NOXCO2 MPG NMHC HC CO NOX CO2 MPG4729 AsRcvd 75 0.090 0.105 1.09 0.189 241.5 36.6 0.099 0.117 1.45 0.159 278.9 31.64755 1 50 0.034 0.053 1.22 0.181 264.4 32.0 0.085 0.106 1.63 0.158 301.1 28.14759 2 50 0.045 0.064 1.06 0.149 265.9 31.8 0.102 0.133 1.68 0.146 303.6 27.84802 3 50 0.048 0.073 1.14 0.150 257.5 33.4 0.094 0.123 1.60 0.175 293.5 29.24747 4 50 0.042 0.059 0.89 0.151 271.5 30.0 0.111 0.141 1.48 0.136 302.0 26.94821 5 50 0.039 0.058 1.26 0.170 260.3 32.8 0.087 0.115 1.82 0.160 300.7 28.44776 1 75 0.041 0.057 0.80 0.176 256.0 33.1 0.071 0.090 0.99 0.176 290.3 29.24782 2 75 0.054 0.073 1.56 0.238 253.5 33.2 0.078 0.111 1.95 0.161 293.0 28.74733 3 75 0.045 0.062 0.93 0.142 251.6 34.2 0.071 0.094 1.34 0.116 289.9 29.64767 4 75 0.038 0.055 1.01 0.176 256.3 31.7 0.064 0.082 1.04 0.139 295.0 27.64808 5 75 0.051 0.067 1.53 0.159 256.8 33.2 0.071 0.094 1.50 0.143 289.0 29.64845 6 75 0.037 0.061 1.42 0.145 250.8 34.8 0.057 0.079 1.25 0.156 292.9 29.84855 6 75 0.025 0.051 0.68 0.146 249.1 35.2 0.063 0.089 1.28 0.124 285.5 30.64870 7 75 0.035 0.057 1.19 0.172 253.9 33.4 0.060 0.084 1.13 0.146 287.9 29.54875 7 75 0.024 0.040 0.67 0.156 252.9 33.7 0.054 0.071 0.90 0.158 291.2 29.2B-7Test Results - Vehicle 006Bag 1Bag 2Test Fuel Temp NMHC HC CO NOXCO2 MPG NMHC HC CO NOX CO2 MPG4726 AsRcvd 75 0.152 0.180 3.657 0.306 401.7 21.8 0.016 0.027 0.623 0.028 361.0 24.64778 1 50 0.327 0.381 5.19 0.745 435.3 19.2 0.019 0.036 0.82 0.037 385.2 22.14770 2 50 0.315 0.368 4.42 0.605 436.7 19.1 0.012 0.026 0.73 0.053 382.2 22.24791 3 50 0.352 0.412 5.95 0.770 432.8 19.5 0.018 0.041 1.13 0.046 383.1 22.54765 4 50 0.301 0.356 4.81 0.782 423.8 18.9 0.016 0.038 0.85 0.042 382.4 21.34815 5 50 0.291 0.362 5.69 0.824 433.2 19.4 0.013 0.029 0.94 0.040 382.8 22.44781 1 75 0.144 0.180 3.72 0.380 413.8 20.3 0.020 0.042 1.20 0.047 371.3 22.94804 2 75 0.159 0.201 4.54 0.444 415.2 20.1 0.015 0.049 2.57 0.163 377.6 22.34753 3 75 0.135 0.173 4.06 0.380 414.8 20.5 0.008 0.029 1.00 0.036 373.4 23.14760 4 75 0.156 0.195 3.79 0.387 420.9 19.2 0.019 0.044 0.64 0.056 380.3 21.54823 5 75 0.108 0.156 3.77 0.391 403.0 21.1 0.010 0.037 1.68 0.076 370.1 23.14877 6 75 0.153 0.197 4.74 0.472 405.3 21.3 0.014 0.036 1.18 0.056 367.2 23.94881 6 75 0.142 0.186 4.20 0.372 413.2 20.9 0.013 0.035 0.81 0.054 371.3 23.64841 7 75 0.164 0.210 4.51 0.402 412.2 20.4 0.006 0.031 0.72 0.046 378.8 22.54849 7 75 0.144 0.182 3.62 0.349 410.9 20.5 0.013 0.032 0.64 0.050 375.3 22.7Bag3 FTPCompositeTest Fuel Temp NMHC HC CO NOXCO2 MPG NMHC HC CO NOX CO2 MPG4726 AsRcvd 75 0.023 0.037 1.17 0.158 345.2 25.6 0.046 0.062 1.40 0.122 365.1 24.24778 1 50 0.025 0.049 1.75 0.323 364.4 23.2 0.085 0.111 1.98 0.263 389.8 21.74770 2 50 0.032 0.049 1.88 0.291 364.9 23.1 0.080 0.104 1.81 0.233 388.8 21.74791 3 50 0.035 0.051 1.89 0.287 356.1 24.1 0.092 0.120 2.34 0.262 386.0 22.24765 4 50 0.028 0.045 1.30 0.342 353.4 23.0 0.078 0.106 1.79 0.278 383.0 21.24815 5 50 0.018 0.047 1.97 0.316 359.1 23.8 0.072 0.103 2.21 0.279 386.8 22.14781 1 75 0.032 0.052 1.98 0.286 353.0 23.9 0.049 0.073 1.94 0.182 375.1 22.64804 2 75 0.029 0.055 2.80 0.307 348.7 24.1 0.049 0.082 3.04 0.261 377.4 22.34753 3 75 0.030 0.050 1.69 0.223 357.3 24.1 0.040 0.065 1.82 0.158 377.6 22.84760 4 75 0.030 0.054 1.53 0.244 361.4 22.5 0.051 0.078 1.54 0.176 383.5 21.24823 5 75 0.034 0.052 1.88 0.277 356.2 24.0 0.037 0.066 2.17 0.197 373.1 22.94877 6 75 0.021 0.046 1.95 0.281 346.5 25.2 0.045 0.072 2.13 0.204 369.4 23.64881 6 75 0.016 0.042 1.51 0.240 346.8 25.2 0.041 0.068 1.71 0.171 373.3 23.44841 7 75 0.019 0.048 1.26 0.249 349.3 24.4 0.042 0.073 1.66 0.175 377.6 22.54849 7 75 0.022 0.045 1.30 0.275 350.0 24.3 0.043 0.067 1.44 0.174 375.8 22.6B-8Test Results - Vehicle 007Bag 1Bag 2Test Fuel Temp NMHC HC CO NOXCO2 MPG NMHC HC CO NOX CO2 MPG4794 AsRcvd 75 0.234 0.263 1.85 0.645 436.9 20.2 0.015 0.023 0.47 0.104 465.9 19.14920 1 50 0.329 0.390 2.45 0.971 486.1 17.4 0.010 0.020 0.04 0.290 491.8 17.34953 2 50 0.454 0.547 3.13 1.378 504.1 16.7 0.000 0.026 0.03 0.345 503.1 16.94835 3 50 0.300 0.369 2.88 0.795 485.8 17.6 0.015 0.023 0.13 0.066 483.5 17.94828 4 50 0.311 0.368 2.51 0.916 479.7 16.9 0.003 0.011 0.06 0.102 478.0 17.14927 5 50 0.329 0.391 2.83 1.434 497.7 17.1 0.012 0.026 0.59 0.340 492.8 17.54895 1 75 0.253 0.281 1.95 0.788 452.3 18.7 0.012 0.021 0.08 0.136 473.6 18.04885 2 75 0.232 0.271 1.91 0.805 438.4 19.3 0.011 0.024 1.99 0.192 469.6 18.04848 3 75 0.225 0.271 1.82 0.704 446.7 19.2 0.004 0.023 0.82 0.098 480.3 18.04944 4 75 0.223 0.266 1.53 1.152 456.1 17.8 0.007 0.018 0.00 0.326 483.6 16.94956 5 75 0.233 0.283 2.22 1.151 452.7 18.9 0.013 0.032 1.06 0.411 482.3 17.84966 6 75 0.241 0.296 1.73 1.197 455.5 19.2 0.013 0.025 0.00 0.363 482.9 18.24971 6 75 0.222 0.270 1.48 1.015 453.4 19.3 0.011 0.025 0.00 0.292 478.6 18.44983 7 75 0.244 0.293 1.62 0.912 453.3 18.7 0.011 0.020 0.00 0.222 482.0 17.84989 7 75 0.239 0.288 1.69 0.828 447.6 19.0 0.014 0.026 0.00 0.167 483.1 17.7Bag3 FTPCompositeTest Fuel Temp NMHC HC CO NOXCO2 MPG NMHC HC CO NOX CO2 MPG4794 AsRcvd 75 0.029 0.044 0.74 0.246 385.3 23.0 0.064 0.078 0.83 0.255 437.7 20.34920 1 50 0.017 0.034 0.22 0.249 407.1 20.9 0.078 0.101 0.59 0.420 467.4 18.24953 2 50 0.002 0.036 0.46 0.672 400.5 21.2 0.094 0.137 0.79 0.649 475.1 17.94835 3 50 0.020 0.033 0.30 0.227 394.3 21.9 0.075 0.097 0.75 0.261 459.5 18.84828 4 50 0.006 0.023 0.15 0.318 393.8 20.8 0.067 0.088 0.60 0.330 455.2 18.04927 5 50 0.015 0.035 0.48 0.620 402.8 21.4 0.079 0.104 1.02 0.644 469.1 18.34895 1 75 0.029 0.032 0.45 0.228 388.1 21.9 0.066 0.078 0.57 0.296 445.7 19.14885 2 75 0.030 0.047 2.35 0.265 381.8 22.1 0.062 0.082 2.07 0.339 439.0 19.24848 3 75 0.017 0.032 0.85 0.246 390.6 22.1 0.053 0.077 1.04 0.264 448.7 19.24944 4 75 0.006 0.027 0.13 0.359 403.9 20.3 0.051 0.072 0.35 0.506 456.0 17.94956 5 75 0.028 0.056 2.41 0.463 399.2 21.4 0.063 0.090 1.67 0.579 453.4 18.94966 6 75 0.020 0.037 0.25 0.403 403.4 21.8 0.062 0.084 0.43 0.547 455.3 19.34971 6 75 0.019 0.041 0.29 0.487 401.0 21.9 0.057 0.080 0.39 0.496 452.0 19.44983 7 75 0.017 0.035 0.18 0.289 411.7 20.8 0.061 0.081 0.39 0.384 456.7 18.74989 7 75 0.019 0.040 0.26 0.432 401.1 21.3 0.062 0.084 0.42 0.377 453.2 18.9B-9Test Results - Vehicle 008Bag 1Bag 2Test Fuel Temp NMHC HC CO NOXCO2 MPG NMHC HC CO NOX CO2 MPG5136 AsRcvd 75 0.240 0.265 1.80 0.605 584.4 15.1 0.009 0.017 0.12 0.061 567.9 15.75169 1 50 0.380 0.436 2.32 0.519 613.4 13.8 0.014 0.019 0.08 0.033 587.3 14.55203 2 50 0.491 0.552 1.80 0.697 636.6 13.3 0.009 0.020 0.17 0.027 600.6 14.25212 3 50 0.712 0.789 7.10 0.471 644.9 13.2 0.007 0.017 0.17 0.058 595.7 14.55163 4 50 0.349 0.396 2.15 0.572 630.9 12.9 0.007 0.018 0.10 0.022 618.4 13.25235 5 50 0.431 0.482 2.53 0.618 630.8 13.5 0.005 0.013 0.34 0.060 599.9 14.45223 1 75 0.349 0.394 1.88 0.466 615.0 13.8 0.018 0.020 0.21 0.054 579.9 14.75252 2 75 0.271 0.310 1.33 0.496 598.9 14.1 0.013 0.017 0.33 0.060 584.0 14.65228 3 75 0.345 0.390 1.88 0.588 615.4 14.0 0.006 0.011 0.28 0.045 587.1 14.75207 4 75 0.250 0.289 1.55 0.520 593.3 13.7 0.007 0.013 0.16 0.024 583.9 14.05149 5 75 0.301 0.346 2.61 0.593 586.6 14.6 0.004 0.016 0.25 0.070 579.2 14.95271 6 75 0.284 0.322 1.60 0.552 581.4 15.1 0.008 0.013 0.25 0.021 578.7 15.25276 6 75 0.271 0.308 1.59 0.588 606.5 14.4 0.009 0.014 0.21 0.024 591.4 14.95184 7 75 0.252 0.291 1.78 0.528 580.5 14.7 0.013 0.022 0.11 0.035 576.2 14.95187 7 75 0.254 0.297 1.68 0.505 590.3 14.4 0.017 0.023 0.19 0.024 579.5 14.8Bag3 FTPCompositeTest Fuel Temp NMHC HC CO NOXCO2 MPG NMHC HC CO NOX CO2 MPG5136 AsRcvd 75 0.018 0.030 0.20 0.215 493.7 18.0 0.059 0.072 0.49 0.216 550.9 16.15169 1 50 0.011 0.026 0.10 0.244 495.8 17.2 0.089 0.107 0.55 0.192 567.6 15.05203 2 50 0.014 0.022 0.20 0.283 506.8 16.8 0.110 0.131 0.52 0.236 582.3 14.65212 3 50 0.014 0.028 0.29 0.177 514.0 16.8 0.155 0.180 1.64 0.176 583.5 14.85163 4 50 0.008 0.024 0.10 0.243 515.6 15.9 0.078 0.098 0.52 0.197 592.7 13.85235 5 50 0.006 0.015 0.18 0.289 517.9 16.6 0.094 0.111 0.75 0.239 583.8 14.75223 1 75 0.009 0.018 0.10 0.210 498.2 17.1 0.084 0.097 0.52 0.182 564.7 15.15252 2 75 0.009 0.020 0.25 0.289 494.3 17.2 0.065 0.078 0.51 0.213 562.5 15.15228 3 75 0.012 0.024 0.24 0.239 505.8 17.1 0.078 0.093 0.60 0.211 570.7 15.25207 4 75 0.011 0.022 0.13 0.237 503.7 16.3 0.058 0.073 0.44 0.185 563.7 14.55149 5 75 0.015 0.026 0.22 0.298 485.8 17.7 0.069 0.087 0.73 0.241 555.1 15.55271 6 75 0.008 0.020 0.19 0.209 490.5 17.9 0.065 0.079 0.51 0.183 555.0 15.85276 6 75 0.008 0.019 0.16 0.185 491.2 17.9 0.063 0.077 0.48 0.185 567.0 15.55184 7 75 0.014 0.026 0.17 0.237 494.6 17.3 0.063 0.079 0.47 0.193 554.7 15.45187 7 75 0.008 0.022 0.23 0.253 496.3 17.2 0.064 0.080 0.51 0.187 558.9 15.3B-10Test Results - Vehicle 009Bag 1Bag 2Test Fuel Temp NMHC HC CO NOXCO2 MPG NMHC HC CO NOX CO2 MPG5351 AsRcvd 75 0.119 0.128 1.25 0.167 352.1 25.1 0.010 0.009 0.07 0.019 385.9 23.15430 1 50 0.241 0.268 1.71 0.253 433.8 19.5 0.010 0.014 0.06 0.013 450.2 18.95366 2 50 0.238 0.263 1.78 0.197 436.9 19.3 0.014 0.019 0.07 0.011 440.4 19.35413 3 50 0.232 0.264 2.41 0.227 435.5 19.7 0.006 0.006 0.13 0.016 446.8 19.45379 4 50 0.205 0.232 1.50 0.282 436.3 18.6 0.004 0.012 0.04 0.044 446.8 18.35393 5 50 0.247 0.278 2.68 0.206 434.7 19.6 0.001 0.010 0.14 0.024 442.1 19.55439 1 75 0.136 0.158 1.36 0.188 410.7 20.6 0.012 0.016 0.11 0.009 436.5 19.55372 2 75 0.119 0.138 1.15 0.192 414.5 20.4 0.002 0.010 0.23 0.010 444.5 19.15361 3 75 0.114 0.131 1.63 0.149 404.6 21.3 0.002 0.007 0.16 0.002 424.6 20.45385 4 75 0.106 0.126 1.25 0.189 408.3 20.0 0.000 0.005 0.02 0.021 435.3 18.85449 5 75 0.127 0.146 1.37 0.196 414.7 20.7 0.005 0.007 0.20 0.015 435.6 19.85421 6 75 0.138 0.161 1.55 0.189 409.2 21.4 0.008 0.010 0.03 0.020 438.7 20.15427 6 75 0.163 0.187 1.72 0.191 415.9 21.0 0.005 0.009 0.11 0.016 443.8 19.85403 7 75 0.136 0.157 1.03 0.180 413.3 20.6 0.010 0.012 0.08 0.020 435.0 19.75407 7 75 0.135 0.155 1.47 0.192 407.4 20.9 0.005 0.007 0.05 0.019 433.0 19.8Bag3 FTPCompositeTest Fuel Temp NMHC HC CO NOXCO2 MPG NMHC HC CO NOX CO2 MPG5351 AsRcvd 75 0.003 0.005 0.05 0.014 302.4 29.4 0.031 0.033 0.31 0.049 355.9 25.05430 1 50 0.005 0.005 0.02 0.007 378.9 22.5 0.057 0.064 0.39 0.061 427.2 19.95366 2 50 0.009 0.015 0.05 0.017 375.4 22.7 0.059 0.068 0.42 0.051 421.9 20.15413 3 50 0.000 0.002 0.13 0.016 374.5 23.1 0.051 0.058 0.61 0.060 424.6 20.45379 4 50 0.000 0.007 0.02 0.023 377.8 21.7 0.045 0.056 0.34 0.087 425.6 19.25393 5 50 0.004 0.008 0.18 0.015 378.3 22.8 0.053 0.065 0.68 0.059 423.0 20.35439 1 75 0.006 0.010 0.08 0.016 372.4 22.9 0.036 0.044 0.36 0.048 413.5 20.65372 2 75 0.005 0.008 0.02 0.016 378.0 22.5 0.027 0.036 0.36 0.049 420.0 20.25361 3 75 0.009 0.011 0.07 0.010 365.7 23.7 0.027 0.034 0.44 0.035 404.3 21.45385 4 75 0.005 0.008 0.04 0.028 369.4 22.2 0.023 0.031 0.28 0.058 411.6 19.95449 5 75 0.002 0.009 0.20 0.013 371.5 23.2 0.030 0.036 0.44 0.052 413.7 20.85421 6 75 0.003 0.010 0.07 0.015 373.3 23.6 0.034 0.041 0.36 0.054 414.6 21.25427 6 75 0.004 0.011 0.15 0.016 371.9 23.7 0.037 0.046 0.45 0.053 418.3 21.05403 7 75 0.006 0.012 0.01 0.020 375.7 22.8 0.035 0.042 0.26 0.053 414.2 20.65407 7 75 0.004 0.007 0.04 0.017 372.9 23.0 0.032 0.037 0.34 0.054 411.2 20.8B-11Test Results - Vehicle 010Bag 1Bag 2Test Fuel Temp NMHC HC CO NOXCO2 MPG NMHC HC CO NOX CO2 MPG25649 AsRcvd 75 0.197 0.232 2.40 0.125 469.4 18.8 0.015 0.037 0.20 0.007 467.1 19.04737 1 50 0.331 0.396 7.14 0.127 442.6 18.8 0.011 0.030 0.07 0.010 438.7 19.44746 2 50 0.318 0.382 5.22 0.127 443.4 18.8 0.023 0.042 0.16 0.002 436.6 19.54766 3 50 0.325 0.388 7.17 0.124 440.0 19.1 0.017 0.035 0.10 0.004 438.0 19.84771 4 50 0.314 0.377 6.03 0.127 441.9 18.1 0.014 0.032 0.15 0.008 434.8 18.84820 5 50 0.253 0.318 5.48 0.139 427.7 19.7 0.012 0.036 0.09 0.005 428.6 20.14787 1 75 0.177 0.218 1.98 0.122 428.8 19.7 0.022 0.041 0.09 0.013 427.7 19.94752 2 75 0.163 0.202 2.54 0.092 425.4 19.8 0.000 0.021 0.12 0.004 423.8 20.14761 3 75 0.192 0.241 2.74 0.094 422.6 20.3 0.027 0.045 0.22 0.005 426.6 20.34793 4 75 0.149 0.189 2.12 0.079 400.4 20.3 0.016 0.036 0.10 0.011 420.1 19.54807 5 75 0.176 0.226 2.67 0.083 406.8 20.9 0.018 0.036 0.07 0.010 419.3 20.64862 6 75 0.142 0.193 2.63 0.092 408.5 21.3 0.012 0.040 0.15 0.005 420.9 20.94871 6 75 0.175 0.223 2.72 0.111 413.4 21.0 0.017 0.043 0.24 0.004 409.3 21.54840 7 75 0.139 0.190 2.37 0.092 404.2 21.0 0.000 0.032 0.13 0.001 421.3 20.34844 7 75 0.173 0.216 2.62 0.092 402.0 21.0 0.010 0.034 0.15 0.007 418.4 20.4Bag3 FTPCompositeTest Fuel Temp NMHC HC CO NOXCO2 MPG NMHC HC CO NOX CO2 MPG25649 AsRcvd 75 0.028 0.053 0.29 0.023 377.7 23.5 0.056 0.082 0.68 0.036 443.0 20.04737 1 50 0.012 0.030 0.06 0.014 351.7 24.2 0.078 0.106 1.53 0.035 415.6 20.44746 2 50 0.015 0.038 0.17 0.012 356.3 23.9 0.082 0.111 1.21 0.030 416.0 20.44766 3 50 0.017 0.036 0.12 0.014 346.2 25.0 0.081 0.109 1.57 0.031 413.2 20.84771 4 50 0.013 0.033 0.14 0.015 358.5 22.8 0.076 0.104 1.37 0.035 415.3 19.64820 5 50 0.011 0.034 0.17 0.016 343.6 25.1 0.062 0.094 1.23 0.035 405.0 21.24787 1 75 0.021 0.040 0.15 0.047 349.2 24.4 0.054 0.078 0.50 0.045 406.4 20.94752 2 75 0.010 0.029 0.17 0.022 350.0 24.3 0.037 0.061 0.63 0.027 403.8 21.04761 3 75 0.025 0.044 0.14 0.011 352.8 24.5 0.061 0.086 0.72 0.025 405.5 21.34793 4 75 0.017 0.035 0.10 0.018 344.5 23.8 0.044 0.068 0.52 0.027 395.3 20.74807 5 75 0.015 0.038 0.10 0.019 343.4 25.1 0.050 0.076 0.62 0.027 395.8 21.74862 6 75 0.015 0.041 0.17 0.017 344.3 25.5 0.040 0.072 0.67 0.026 397.3 22.14871 6 75 0.013 0.035 0.23 0.020 339.8 25.9 0.049 0.078 0.75 0.031 391.1 22.44840 7 75 0.009 0.038 0.13 0.019 343.4 24.9 0.031 0.066 0.60 0.025 396.3 21.54844 7 75 0.014 0.036 0.21 0.022 338.7 25.2 0.045 0.072 0.68 0.029 393.1 21.7B-12Test Results - Vehicle 011Bag 1Bag 2Test Fuel Temp NMHC HC CO NOXCO2 MPG NMHC HC CO NOX CO2 MPG5354 AsRcvd 75 0.165 0.181 1.12 0.072 420.6 21.1 0.015 0.014 0.00 0.014 420.8 21.25431 1 50 0.259 0.295 0.99 0.126 458.2 18.5 0.011 0.017 0.00 0.012 435.2 19.65412 2 50 0.344 0.387 1.69 0.173 453.6 18.6 0.013 0.018 0.00 0.021 437.9 19.45397 3 50 0.248 0.284 1.71 0.111 451.6 19.0 0.011 0.014 0.00 0.001 433.8 20.05370 4 50 0.246 0.284 1.26 0.147 463.4 17.6 0.019 0.021 0.00 0.023 442.8 18.55426 5 50 0.208 0.242 1.48 0.101 452.7 18.9 0.014 0.014 0.00 0.007 435.4 19.85404 1 75 0.091 0.107 0.75 0.106 424.4 20.0 0.006 0.017 0.00 0.004 432.8 19.75448 2 75 0.089 0.105 0.77 0.142 421.3 20.1 0.006 0.012 0.00 0.010 432.8 19.75443 3 75 0.085 0.102 0.68 0.135 420.1 20.6 0.006 0.011 0.00 0.004 427.2 20.35435 4 75 0.077 0.094 0.86 0.109 423.8 19.3 0.011 0.012 0.00 0.006 432.7 18.95374 5 75 0.099 0.116 0.93 0.101 422.8 20.3 0.008 0.013 0.00 0.010 434.5 19.85380 6 75 0.091 0.107 0.68 0.098 424.1 20.7 0.010 0.010 0.00 0.006 429.9 20.55382 6 75 0.087 0.105 1.01 0.098 421.2 20.8 0.004 0.011 0.00 0.008 430.0 20.55386 7 75 0.074 0.089 0.72 0.099 420.9 20.3 0.005 0.009 0.00 0.007 430.2 19.95388 7 75 0.082 0.098 0.99 0.104 414.4 20.6 0.012 0.016 0.00 0.012 429.9 19.9Bag3 FTPCompositeTest Fuel Temp NMHC HC CO NOXCO2 MPG NMHC HC CO NOX CO2 MPG5354 AsRcvd 75 0.010 0.010 0.00 0.019 347.9 25.6 0.045 0.047 0.23 0.028 400.8 22.25431 1 50 0.001 0.006 0.00 0.053 360.6 23.7 0.060 0.072 0.20 0.047 419.5 20.35412 2 50 0.004 0.008 0.00 0.104 351.1 24.2 0.079 0.092 0.35 0.075 417.2 20.45397 3 50 0.004 0.009 0.00 0.066 357.2 24.3 0.058 0.069 0.35 0.042 416.4 20.85370 4 50 0.007 0.012 0.00 0.034 358.9 22.8 0.063 0.073 0.26 0.052 424.0 19.35426 5 50 0.003 0.007 0.00 0.004 354.7 24.3 0.051 0.059 0.31 0.026 416.8 20.65404 1 75 0.008 0.010 0.00 0.079 358.3 23.8 0.024 0.034 0.15 0.046 410.6 20.85448 2 75 0.001 0.008 0.00 0.036 359.6 23.7 0.022 0.030 0.16 0.044 410.3 20.75443 3 75 0.002 0.009 0.00 0.054 354.4 24.4 0.022 0.029 0.14 0.045 405.7 21.35435 4 75 0.008 0.009 0.00 0.041 352.2 23.3 0.024 0.028 0.18 0.037 408.8 20.05374 5 75 0.002 0.009 0.00 0.037 356.7 24.2 0.025 0.033 0.20 0.037 410.7 21.05380 6 75 0.003 0.006 0.00 0.047 353.8 24.9 0.025 0.029 0.14 0.036 407.8 21.65382 6 75 0.006 0.008 0.00 0.009 354.6 24.8 0.021 0.030 0.21 0.027 407.5 21.65386 7 75 0.007 0.007 0.00 0.027 349.4 24.5 0.020 0.025 0.15 0.032 406.1 21.15388 7 75 0.006 0.008 0.00 0.032 355.5 24.1 0.025 0.031 0.20 0.036 406.2 21.1B-13Test Results - Vehicle 012Bag 1Bag 2Test Fuel Temp NMHC HC CO NOXCO2 MPG NMHC HC CO NOX CO2 MPG4993 AsRcvd 75 0.245 0.263 1.63 0.092 445.2 19.8 0.032 0.032 0.00 0.003 447.1 19.95133 1 50 0.170 0.201 2.08 0.069 485.8 17.4 0.011 0.017 0.01 0.006 452.0 18.95142 2 50 0.065 0.081 0.39 0.115 464.7 18.3 0.004 0.012 0.05 0.069 455.8 18.75079 3 50 0.206 0.243 3.67 0.129 496.5 17.2 0.010 0.017 0.02 0.006 468.2 18.55073 4 50 0.156 0.186 1.39 0.202 485.3 16.8 0.015 0.021 0.00 0.112 458.7 17.95018 5 50 0.224 0.263 3.37 0.083 490.7 17.4 0.011 0.015 0.00 0.048 455.0 18.95111 1 75 0.100 0.120 0.95 0.105 453.6 18.7 0.010 0.019 0.01 0.024 465.8 18.35037 2 75 0.094 0.116 1.26 0.115 440.1 19.2 0.007 0.012 0.00 0.055 464.5 18.35006 3 75 0.086 0.106 0.76 0.078 453.7 19.0 0.011 0.017 0.00 0.039 449.8 19.35124 4 75 0.069 0.080 0.27 0.137 450.1 18.2 0.012 0.015 0.00 0.104 453.2 18.15155 5 75 0.081 0.110 1.18 0.100 440.8 19.5 0.001 0.009 0.20 0.091 452.1 19.15053 6 75 0.087 0.108 0.85 0.064 452.0 19.4 0.011 0.015 0.00 0.004 462.1 19.15056 6 75 0.093 0.114 0.87 0.056 454.0 19.3 0.007 0.013 0.01 0.012 460.4 19.15091 7 75 0.070 0.089 0.59 0.076 459.4 18.6 0.014 0.020 0.00 0.022 464.1 18.45102 7 75 0.074 0.095 0.57 0.073 453.8 18.8 0.008 0.012 0.01 0.014 460.8 18.6Bag3 FTPCompositeTest Fuel Temp NMHC HC CO NOXCO2 MPG NMHC HC CO NOX CO2 MPG4993 AsRcvd 75 0.017 0.025 0.11 0.024 382.7 23.2 0.072 0.078 0.37 0.027 429.0 20.75133 1 50 0.017 0.025 0.10 0.028 397.0 21.5 0.046 0.057 0.47 0.025 443.9 19.25142 2 50 0.012 0.021 0.08 0.038 393.0 21.7 0.019 0.029 0.13 0.070 440.4 19.35079 3 50 0.007 0.015 0.06 0.010 395.7 21.9 0.050 0.063 0.79 0.032 454.1 19.05073 4 50 0.015 0.019 0.00 0.069 392.6 20.9 0.044 0.055 0.29 0.119 446.1 18.35018 5 50 0.010 0.015 0.00 0.023 387.0 22.3 0.055 0.066 0.70 0.048 443.7 19.45111 1 75 0.013 0.022 0.10 0.040 405.5 21.0 0.030 0.041 0.23 0.046 446.7 19.15037 2 75 0.012 0.020 0.04 0.122 377.7 22.5 0.026 0.036 0.27 0.086 435.6 19.55006 3 75 0.011 0.020 0.11 0.015 390.3 22.2 0.027 0.036 0.19 0.040 434.3 19.95124 4 75 0.010 0.019 0.03 0.024 389.0 21.1 0.023 0.030 0.06 0.089 434.9 18.85155 5 75 0.016 0.026 0.19 0.144 393.3 21.9 0.022 0.035 0.40 0.107 433.5 19.95053 6 75 0.007 0.017 0.08 0.031 397.5 22.1 0.026 0.035 0.20 0.023 442.2 19.95056 6 75 0.012 0.022 0.13 0.035 399.6 22.0 0.026 0.036 0.22 0.028 442.4 19.95091 7 75 0.011 0.023 0.09 0.018 394.0 21.7 0.025 0.035 0.15 0.032 443.8 19.35102 7 75 0.011 0.020 0.14 0.058 386.3 22.1 0.023 0.032 0.16 0.038 438.9 19.5B-14Test Results - Vehicle 013Bag 1Bag 2Test Fuel Temp NMHC HC CO NOXCO2 MPG NMHC HC CO NOX CO2 MPG5150 AsRcvd 75 0.195 0.252 1.81 0.299 690.6 12.8 0.028 0.082 0.39 0.020 684.6 13.05211 1 50 0.353 0.436 3.28 0.546 727.5 11.6 0.024 0.079 0.46 0.021 713.0 12.05173 2 50 0.297 0.375 2.02 0.547 729.4 11.6 0.033 0.093 0.53 0.025 703.9 12.15170 3 50 0.360 0.449 4.43 0.562 767.0 11.2 0.031 0.091 0.50 0.013 718.7 12.05247 4 50 0.359 0.436 3.03 0.392 727.3 11.2 0.025 0.070 0.46 0.022 694.7 11.85196 5 50 0.340 0.412 4.83 0.508 724.6 11.8 0.031 0.082 0.42 0.021 706.8 12.25240 1 75 0.202 0.267 1.78 0.341 700.3 12.1 0.014 0.067 0.44 0.018 703.2 12.15222 2 75 0.229 0.295 1.99 0.345 683.4 12.4 0.034 0.082 0.46 0.017 686.5 12.45261 3 75 0.220 0.285 2.74 0.282 691.4 12.4 0.014 0.061 0.40 0.019 696.9 12.45208 4 75 0.183 0.244 1.80 0.391 697.7 11.7 0.025 0.074 0.38 0.015 695.6 11.85201 5 75 0.211 0.273 3.00 0.430 699.5 12.2 0.010 0.050 0.43 0.048 704.2 12.25227 6 75 0.192 0.259 2.51 0.356 689.8 12.7 0.026 0.076 0.51 0.015 703.4 12.55231 6 75 0.212 0.281 2.73 0.388 694.8 12.6 0.028 0.082 0.53 0.014 699.9 12.65158 7 75 0.194 0.258 2.06 0.333 681.0 12.5 0.000 0.088 0.49 0.020 684.5 12.55160 7 75 0.174 0.241 1.71 0.324 682.0 12.5 0.032 0.093 0.48 0.018 693.6 12.3Bag3 FTPCompositeTest Fuel Temp NMHC HC CO NOXCO2 MPG NMHC HC CO NOX CO2 MPG5150 AsRcvd 75 0.028 0.066 0.34 0.078 580.8 15.3 0.063 0.113 0.67 0.094 657.4 13.55211 1 50 0.018 0.056 0.27 0.067 613.8 13.9 0.091 0.147 0.99 0.142 688.8 12.45173 2 50 0.019 0.058 0.27 0.061 600.2 14.2 0.084 0.142 0.77 0.143 680.7 12.55170 3 50 0.026 0.065 0.33 0.068 630.8 13.7 0.098 0.158 1.27 0.142 704.5 12.35247 4 50 0.015 0.051 0.30 0.079 610.4 13.4 0.091 0.140 0.95 0.114 678.3 12.05196 5 50 0.019 0.052 0.33 0.059 595.0 14.5 0.092 0.142 1.31 0.133 679.8 12.65240 1 75 0.018 0.058 0.31 0.069 604.7 14.1 0.054 0.106 0.68 0.099 675.5 12.65222 2 75 0.021 0.056 0.28 0.056 602.4 14.1 0.071 0.119 0.73 0.096 662.7 12.85261 3 75 0.016 0.048 0.36 0.043 598.6 14.5 0.057 0.104 0.87 0.080 668.7 12.95208 4 75 0.019 0.055 0.34 0.076 612.3 13.4 0.056 0.104 0.66 0.110 673.2 12.15201 5 75 0.040 0.079 0.36 0.078 614.3 14.0 0.060 0.104 0.94 0.135 678.6 12.75227 6 75 0.017 0.055 0.37 0.055 615.2 14.3 0.058 0.108 0.88 0.097 676.4 13.05231 6 75 0.016 0.054 0.38 0.049 613.0 14.3 0.063 0.116 0.94 0.101 674.9 13.05158 7 75 0.003 0.065 0.38 0.079 590.3 14.5 0.041 0.117 0.79 0.101 657.9 13.05160 7 75 0.017 0.063 0.40 0.078 591.6 14.4 0.057 0.115 0.71 0.098 663.2 12.9B-15Test Results - Vehicle 014Bag 1Bag 2Test Fuel Temp NMHC HC CO NOXCO2 MPG NMHC HC CO NOX CO2 MPG4891 AsRcvd 75 0.158 0.159 1.11 0.150 471.0 18.8 0.007 0.013 0.03 0.091 462.5 19.24996 1 50 0.246 0.286 1.91 0.284 499.0 17.0 0.015 0.021 0.00 0.012 483.4 17.65017 2 50 0.263 0.302 1.47 0.277 491.4 17.2 0.015 0.020 0.00 0.000 483.1 17.64952 3 50 0.231 0.274 2.58 0.228 493.6 17.4 0.006 0.013 0.00 0.037 477.7 18.15002 4 50 0.293 0.341 3.22 0.201 496.6 16.3 0.007 0.013 0.00 0.022 492.2 16.65078 5 50 0.226 0.271 2.97 0.229 487.1 17.5 0.019 0.025 0.00 0.017 481.6 17.95009 1 75 0.134 0.159 0.96 0.168 483.8 17.6 0.012 0.018 0.00 0.004 482.3 17.74959 2 75 0.134 0.160 1.17 0.180 481.8 17.6 0.015 0.022 0.00 0.013 471.4 18.14931 3 75 0.192 0.219 1.38 0.207 479.7 18.0 0.021 0.026 0.03 0.021 468.5 18.55029 4 75 0.099 0.121 0.83 0.133 454.1 18.0 0.019 0.023 0.00 0.047 467.2 17.55106 5 75 0.323 0.359 1.55 0.177 485.4 17.6 0.016 0.021 0.02 0.009 503.6 17.14943 6 75 0.121 0.149 1.47 0.201 477.0 18.4 0.010 0.016 0.00 0.015 472.7 18.64948 6 75 0.180 0.208 1.26 0.143 472.7 18.5 0.016 0.021 0.00 0.004 470.7 18.75061 7 75 0.121 0.151 1.05 0.162 484.8 17.6 0.009 0.016 0.00 0.060 488.2 17.55064 7 75 0.115 0.135 1.27 0.152 480.5 17.7 0.008 0.015 0.00 0.009 479.6 17.8Bag3 FTPCompositeTest Fuel Temp NMHC HC CO NOXCO2 MPG NMHC HC CO NOX CO2 MPG4891 AsRcvd 75 0.009 0.013 0.08 0.015 387.3 23.0 0.039 0.043 0.27 0.082 443.6 20.04996 1 50 0.008 0.020 0.00 0.057 420.1 20.3 0.061 0.075 0.40 0.081 469.2 18.25017 2 50 0.015 0.021 0.03 0.106 417.8 20.4 0.066 0.078 0.31 0.087 466.8 18.24952 3 50 0.006 0.014 0.00 0.008 415.6 20.8 0.053 0.068 0.53 0.069 464.0 18.65002 4 50 0.008 0.014 0.00 0.238 430.3 19.0 0.067 0.082 0.67 0.119 476.1 17.25078 5 50 0.003 0.025 0.20 0.052 416.4 20.7 0.058 0.076 0.67 0.071 464.9 18.55009 1 75 0.010 0.021 0.00 0.041 422.1 20.2 0.037 0.048 0.20 0.048 466.0 18.34959 2 75 0.005 0.014 0.00 0.093 407.7 20.9 0.037 0.048 0.24 0.069 456.0 18.64931 3 75 0.014 0.023 0.11 0.043 413.5 20.9 0.054 0.065 0.33 0.066 455.7 19.05029 4 75 0.014 0.019 0.00 0.019 397.2 20.6 0.034 0.042 0.17 0.057 445.3 18.45106 5 75 0.017 0.025 0.12 0.024 428.6 20.1 0.080 0.092 0.36 0.048 479.2 18.04943 6 75 0.007 0.018 0.01 0.019 408.5 21.6 0.032 0.044 0.31 0.055 456.0 19.34948 6 75 0.013 0.020 0.01 0.015 407.8 21.6 0.049 0.060 0.26 0.036 453.8 19.45061 7 75 0.012 0.024 0.11 0.004 428.2 20.0 0.033 0.046 0.25 0.066 471.0 18.25064 7 75 0.013 0.020 0.05 0.045 423.1 20.2 0.032 0.041 0.28 0.049 464.3 18.4B-16Test Results - Vehicle 015Bag 1Bag 2Test Fuel Temp NMHC HC CO NOXCO2 MPG NMHC HC CO NOX CO2 MPG5269 AsRcvd 75 0.167 0.188 1.38 0.157 431.8 20.5 0.008 0.018 0.00 0.095 420.0 21.25327 1 50 0.109 0.131 1.13 0.051 456.9 18.6 0.015 0.020 0.00 0.046 431.5 19.85315 2 50 0.213 0.241 1.35 0.170 471.4 18.0 0.008 0.014 0.00 0.041 433.6 19.65291 3 50 0.172 0.200 1.64 0.100 402.3 21.4 0.006 0.010 0.00 0.029 401.2 21.65303 4 50 0.172 0.201 1.31 0.160 470.9 17.3 0.005 0.007 0.00 0.033 433.7 18.95325 5 50 0.238 0.269 1.80 0.142 480.4 17.8 0.006 0.012 0.00 0.041 437.1 19.75290 1 75 0.097 0.114 0.67 0.118 449.5 18.9 0.004 0.010 0.00 0.046 432.2 19.75320 2 75 0.121 0.139 0.75 0.133 438.7 19.3 0.002 0.010 0.02 0.034 421.4 20.25311 3 75 0.118 0.141 1.29 0.100 430.3 20.0 0.010 0.015 0.00 0.050 428.4 20.25338 4 75 0.097 0.117 1.07 0.128 443.9 18.4 0.008 0.015 0.00 0.033 427.7 19.25341 5 75 0.137 0.161 1.59 0.109 439.4 19.5 0.007 0.010 0.00 0.040 428.7 20.15329 6 75 0.158 0.185 1.28 0.121 441.3 19.8 0.005 0.012 0.00 0.028 426.2 20.75332 6 75 0.118 0.141 1.24 0.116 442.4 19.8 0.003 0.011 0.00 0.041 427.4 20.65294 7 75 0.091 0.105 0.75 0.119 440.7 19.4 0.000 0.009 0.00 0.054 431.2 19.95301 7 75 0.106 0.127 0.94 0.128 445.0 19.2 0.002 0.012 0.00 0.036 433.5 19.7Bag3 FTPCompositeTest Fuel Temp NMHC HC CO NOXCO2 MPG NMHC HC CO NOX CO2 MPG5269 AsRcvd 75 0.004 0.013 0.00 0.067 360.4 24.7 0.040 0.052 0.29 0.100 406.1 21.95327 1 50 0.009 0.015 0.01 0.028 367.6 23.2 0.033 0.042 0.24 0.042 419.2 20.35315 2 50 0.004 0.010 0.00 0.020 365.2 23.3 0.050 0.060 0.28 0.062 422.6 20.15291 3 50 0.010 0.015 0.04 0.016 374.9 23.1 0.042 0.050 0.35 0.040 394.2 21.95303 4 50 0.001 0.009 0.02 0.018 360.6 22.7 0.039 0.048 0.28 0.055 421.3 19.45325 5 50 0.004 0.010 0.00 0.025 362.9 23.8 0.054 0.065 0.37 0.058 425.7 20.25290 1 75 0.007 0.015 0.00 0.026 363.8 23.5 0.024 0.033 0.14 0.055 417.0 20.45320 2 75 0.009 0.012 0.01 0.026 365.0 23.3 0.029 0.038 0.17 0.053 409.5 20.85311 3 75 0.010 0.014 0.00 0.031 357.4 24.2 0.033 0.041 0.27 0.055 409.3 21.15338 4 75 0.008 0.014 0.04 0.023 371.5 22.0 0.026 0.036 0.23 0.050 415.6 19.75341 5 75 0.004 0.011 0.00 0.041 368.6 23.4 0.033 0.042 0.33 0.055 414.4 20.85329 6 75 0.006 0.015 0.02 0.033 370.5 23.8 0.037 0.049 0.27 0.049 414.1 21.25332 6 75 0.006 0.013 0.01 0.020 368.0 23.9 0.028 0.039 0.26 0.051 414.2 21.25294 7 75 0.004 0.011 0.01 0.020 363.9 23.5 0.020 0.029 0.16 0.058 414.7 20.65301 7 75 0.003 0.013 0.02 0.030 368.8 23.2 0.024 0.036 0.20 0.053 418.1 20.5